There are two correct options:
d) a volume compression
e) adding heat to the system
In fact, we can have a look at the first law of thermodynamics:
[tex]\Delta U = Q-W[/tex]
where
[tex]\Delta U[/tex] is the variation of internal energy
Q is the heat absorbed by the system
W is the work done by the system on the surrounding
It is important to keep in mind the right sign convention for Q and W: Q is positive when the heat is absorbed by the system, while it is negative when it is released by the system; W is positive when it is done by the system on the surrounding, and negative when it is done by the surrounding on the system.
Using this convention, we can see that:
d) when there is a volume compression, the work is done by the surrounding on the system, so the work is negative, and the variation of internal energy is positive due to the negative sign -W in the first law of thermodynamics
e) when heat is added to the system, Q is positive, so the variation of internal energy is positive as well
