Question

Which of these buildings is most likely to have indoor air pollution?

a school with leaks that allow water and heat to be wasted
an office building without a carbon monoxide detector
a tightly sealed house with an unvented water heater

Answer 1

the answer is c. so choose c

Answer 2

The answer would be C, when a heater is on for a long time without having ventilation then carbondixoide  will be converted into carbon monoxide and causes air pollution.