Heat Flows into a Gas in a Piston and the Gas

Multiple Choice

Heat flows into a gas in a piston and the gas performs some work on its surroundings. The amount of work done is less than the heat added. In this situation,

A) the internal energy of the gas decreased.
B) the internal energy of the gas increased.
C) the internal energy of the gas did not change.
D) the gas experienced a phase change.
E) energy is not conserved and so it cannot happen.