In an Isothermal Process, the Pressure on 1 Mol of an Ideal

In an isothermal process, the pressure on 1 mol of an ideal monatomic gas suddenly changes from 4.00 atm to 100.0 atm at 25°C.
-Calculate $\Delta$ V.

A) -5.87 L
B) 6.11 L
C) -6.11 L
D) 5.87 L
E) none of these