Which of the following is a solution for the future that would follow both Dax's and Ava's recommendations?

A.

enactment of laws requiring all people to ride bicycles instead of driving cars

B.

development of gasoline-powered cars that have better fuel efficiency

C.

development of cars that run on fuels that pollute less and cost less than gasoline

D.

enactment of laws that require gasoline to cost more and cause more pollution