Answer:
A)adding heat to the system and having the system do work on the surroundings
Explanation:
The variation in the internal energy of a system (ΔU) is given by the First Law of Thermodynamics. See the equation below:
ΔU = Q + W
Q: Heat added (+) or removed (-) from the system
W: work done on (-) or done by (+) the system
If you add heat (Q +) and have the system do work (W +), you guarantee that th internal energy of the system will increase (ΔU +).
