First of all, in this cycle, the internal energy of gas is the same as the original, so d is wrong;

Looking at the figure again, the gas does positive work from state 1 to state 2 to state 3, and does negative work from state 3 to state 1. Obviously, as can be seen from the figure, negative work is greater than positive work, that is, the net work done by gas to the outside world is negative, so B is wrong;

Because gas does negative work and its internal energy remains unchanged, it releases heat to the outside world, that is, the net heat absorbed by gas from the outside world is negative, so choose A.