Final answer:
After coupling the trailer, the landing gear should be 100% raised to ensure proper securing and prevent damage during transit.
Step-by-step explanation:
The correct answer is A) 100% raised. After the trailer is coupled, the landing gear should be fully raised. This is done to ensure that the trailer is properly secured to the truck and to prevent any damage to the landing gear while in transit. Keeping the landing gear fully raised also helps to improve stability and maneuverability while driving.