Which statement is true of the internal energy of a system and its surroundings during an energy exchange with a negative Δ E sys?

a. The internal energy of the system increases and the internal energy of the surroundings decreases.
b. The internal energy of both the system and the surroundings increases.
c. The internal energy of both the system and the surroundings decreases.
d. The internal energy of the system decreases and the internal energy of the surroundings increases.