Which statement about passive solar heating systems is true? a they do not work in enclosed areas b they generate electricity c their heat cannot be stored d they do not produce electricity

D. They do not produce electricity.

Passive solar heating is a technique where the sun's energy is used for heating spaces. It does not generate electricity but can save substantial electricity by making use of thermal mass. Materials that have a high density such as concrete and bricks absorb and store electricity. Along with operable windows and thermal chimneys,  thermal mass is being utilized to take advantage of sun exposure.

b.

developed countries have tended to improve the environment, while developing countries have tended to damage it.