Unless the Administrator authorizes it, §107.52 prohibits operating a small unmanned aircraft system under Part 107 with a transponder on, and §107.53 prohibits operating with ADS-B Out in transmit mode. The prohibition is on operation with that equipment in use. Remote ID is a Part 89 broadcast, and it is neither a transponder nor ADS-B Out.
The rule
Section 107.52 names ATC transponder equipment. Section 107.53 names Automatic Dependent Surveillance-Broadcast Out. Both sections prohibit operation with the equipment in use, not the installation by itself: a unit that stays off is not a transponder that is on, and it is not ADS-B Out in transmit mode. Both sections open with "unless otherwise authorized by the Administrator." An authorization you hope is implied does not meet that phrase. Operating with the transponder on below 400 feet AGL, with no FAA authorization for the equipment, is still prohibited. ADS-B Out does not have to transmit because the aircraft entered Class C or Class D. Controlled-airspace authorization under §107.41 is a separate issue. It lets you operate in Class B, C, D, or surface Class E designated for an airport when you have prior ATC authorization. It does not switch the transponder or ADS-B Out into transmit.
Remote ID, under Part 89, is the broadcast of identification and location from a standard Remote ID aircraft or a broadcast module. It uses its own message elements. It is not a reply to a secondary-surveillance radar and it is not ADS-B Out. Complying with Remote ID does not satisfy a request you were never given to turn a transponder on, and turning a transponder on does not satisfy Part 89.
Two other onboard facts show up beside this equipment on the same knowledge-test area, and they are easy to merge into it. Loss of GPS signal most directly causes degraded position hold. The pilot should be ready to fly manually. GPS loss is not an immediate loss of all power, and it is not an automatic FAA report. Most small unmanned aircraft control and video links use the unlicensed 2.4 GHz and 5.8 GHz bands. Those bands are shared with Wi-Fi and other devices, so interference can degrade or lose the control link. They are not reserved for aviation. A lost link is handled with the aircraft's planned failsafe. It is not made legal or illegal by an FCC station license obtained for that flight, and it is not cured by transmitting ADS-B Out.
How to apply it
Before launch, confirm the transponder is not operating and ADS-B Out is not in transmit mode, unless you are carrying a specific Administrator authorization that says otherwise. Read that authorization for the equipment it actually names. A LAANC approval for Class B or any other §107.41 airspace is read as an airspace approval. Then set the lost-link behavior while you still have the aircraft in your hands, because 2.4 GHz and 5.8 GHz congestion is a launch planning item. If the GPS picture degrades in flight, fly the aircraft manually rather than assuming position hold is still honest. Yielding to manned aircraft remains §107.37 no matter what electronics are aboard. That duty is on right of way.
A Class C roof and a noisy parking lot
The roof is inside Class C, and you hold a prior authorization to fly there. The manned aircraft around the airport are squawking. Your small unmanned aircraft has a transponder installed from a previous experimental installation, and it has an ADS-B Out unit. Leave both inactive. The airspace authorization did not authorize operation with a transponder on or with ADS-B Out in transmit mode. Remote ID, if this aircraft needs it, is the Part 89 broadcast you already planned. It is not a reason to enable the other two.
The parking lot below the roof is full of phones and access points on 2.4 GHz and 5.8 GHz. You brief the failsafe before launch because interference can drop the control link. Midway through the flight the aircraft stops holding position cleanly and you recognize a GPS degradation. You fly it manually and bring it back. You do not file that moment as an automatic report, and you do not turn ADS-B on to "replace" the lost satellites.
The trap
The equipment item says a transponder is allowed below 400 feet without FAA authorization, or that ADS-B Out must transmit in Class C or Class D. Sections 107.52 and 107.53 both forbid operation with the equipment in use unless the Administrator authorizes it. The §107.41 approval is not that authorization.
The GPS item says loss of signal kills all power at once, or that it generates an automatic FAA report. The direct effect is degraded position hold, and the pilot should be ready to fly manually. The link item says 2.4 GHz and 5.8 GHz are protected aviation spectrum, or that a lost link is illegal unless the pilot first obtains an FCC station license for that flight. The bands are unlicensed and shared. Plan the failsafe. Leave the transponder and ADS-B Out off unless the Administrator has authorized them.
Work the three on the free practice test. The course keeps Remote ID, the transponder prohibition, and the control link in different lessons so the test cannot trade one for another.