An Ideal Gas with an Initial Volume of 3 L

An ideal gas with an initial volume of 3 L at a pressure of 2 atm is compressed adiabatically until it has a volume of 2 L; then it is cooled at constant volume until its temperature drops to its initial value. The final pressure is

A) atm.
B) 2 atm.
C) 3 atm.
D) 4/3 atm.
E) 6 atm.