During a safe uncoupling, what is the purpose of placing wheel chocks?

Answer: C — To check for leaks.

Wheel chocks are used to keep the trailer from moving while you uncouple. When you disconnect the tractor, the trailer could roll forward or backward if the ground isn’t perfectly level or if there’s a breeze, so placing chocks against the trailer wheels locks them in place and prevents a runaway. This safety step protects you and the equipment during the uncoupling process. They aren’t for lifting the trailer, checking for leaks, or aligning tires, which is why those other choices don’t fit.