One mole of an ideal gas at an initial temperature true of `TK` does `6R` joule of work adiabatically. If the ratio of specific heats of this gas at constant pressure and at constant volume is `5//3`, the final temperature of the gas will be
A. `(T + 2.4)K`
B. `(T - 2.4)K`
C. `(T + 4) K`
D. `(T - 4) K`