This graph shows the average temperature inside a room. At time t₁ the heater is turned on. We want to compare the power input to the room (P_{in}) and the power output from the room (P_{out}). For which region(s) on the graph is P_{in} ≠ P_{out}?
[Figure: Temperature vs time graph showing three regions I, II, III with heater turning on at t₁]
a) Only region I.
b) Only region II.
c) Only region III.
d) Only regions I & II.
e) Regions I, II & III.