The correct option is A 2
As the temperature is constant, we will apply Boyle's law, which states that -
PV = constant
Thus, P1V1=P2V2
where P1 and V1 are the initial pressure and volume, and P2 and V2 are the final pressure and volume of the gas.
Thus, P2=P1V1V2
Hence, P2=3 X 57.5
= 2 atm