When heat energy of $1500 \;J$ is suplied to a gas at constant pressure, $2.1 \times 10^5\; N/m^2$, there was an increase in its volume equal to $2.5 \times 10^{-3}m^3$. The increase in its internal energy in joules is :

Question

( A ) 450
( B ) 975
( C ) 2025
( D ) 525