The question is asking: Which of these buildings is most likely to have
indoor air pollution? and we have two scenarios with a problem :
A. a school with leaks that allow water and heat to be wasted
and
C.
a tightly sealed house with and unvented water heater". (B is a
perfectly good scenario without any pollution. ) In A) the problem is a
waste of resources, not pollution, and the answer is C- here, the
pollution from the water heater would stay in the house.
