Question

Over time, the environmental cost of using nonrenewable resources as a unit of fuel energy has decreased. Which behavioral change could have caused this decrease in cost?

A.
People have reduced the use of nonrenewable resources.

B.
People have switched from polluting to nonpolluting types of energy.

C.
People have switched from nonrenewable to renewable forms of energy.

D.
People have used more efficient technologies to extract nonrenewable resources.