You are presented with the quiz "coal is used to produce electricity by burning in inherently modular what?" But you don't know the answer, so you turn to your teacher to ask for hints. He says that "coal is used to produce electricity by burning in coal-fire power stations" and "coal-fired power stations are inherently modular". So, what's the best answer to the question?

OPTIONS:
A). heat
B). stations
C). trees
D). heat energy
E). similar
F). cells
G). adding heat
H). engines
The answer is:
B).