Argon gas is adiabatically compressed to half its volume. If `P, V` and `T` represent the pressure, volume and temperature of the gasous, respectively, at any stage, then the correct equation representing the process is
A. `TV^(2//5) = constant`
B. `VP^(5//3) = constant`
C. `TP^(2//5) = constant`
D. `PT^(2//5) = constant`