As I am reading the problem,i can tell the question gives you two temperatures, two pressures, one volume and asking for the other. this should be an indication that you need to use the following gas formula
P1V1/T1= P2V2/T2
P1= 2.0 atm
V2= 4.0 L
T1= 27= 300 K
P2= 8.0 atm
V2= ?
T2= 327= 600 k
let's plug in the values into the formula
(2.0 x 4.0)/ 300= (8.0 x V2)/ 600 K
V2= 2.0 Liters
answer is D