Answer:
C
Step-by-step explanation:
C - No heat enters or leaves the gas.
Adiabatic Expansion can be defined be saying, it is an expansion in which no heat is added to or no heat is subtracted from the air. This lack of addition or subtraction, cools during the expansion because of the work that would be done by the air. And as such, we can say that No heat enters the gas, and no heat leaves the gas in the same manner.
I hope that's clear enough