Which statement about trailer brakes is correct?

1. This choice is not supported by the Texas CDL handbook or FMCSA combination-vehicle standards.
2. The tractor protection system helps protect tractor air supply during trailer breakaway or major leakage.
3. This statement confuses the tested combination-vehicle rule with an unrelated CDL topic.
4. This answer would create an unsafe coupling, braking, turning, or inspection habit.