TV ^$\gamma$ Is Constant for an Ideal Gas Undergoing an Ideal

TV ^$\gamma$ is constant for an ideal gas undergoing an adiabatic process, where $\gamma$ is the ratio of heat capacities C_p/C_v.This is a direct consequence of:

A) the zeroth law of thermodynamics alone
B) the zeroth law and the ideal gas equation of state
C) the first law of thermodynamics alone
D) the ideal gas equation of state alone
E) the first law and the equation of state