5.6 liter of helium gas at STP is adiabatically compressed to 0.7 liter. Taking the initial temperature to be $$T_1$$, the work done in the process is-

A

$$\frac{9}{8} R T_1$$

B

$$\frac{3}{2} R T_1$$

C

$$\frac{15}{8} R T_1$$

D

$$\frac{9}{2} R T_1$$