lowering parking fees building larger parking lots decreasing the cost of gasoline lowering the cost of bus and subway fares
I gave my students this multiple choice question: City administrators can encourage energy conservation by

Only one answer is correct among these 4 choices:
- lowering parking fees
- building larger parking lots
- decreasing the cost of gasoline
- lowering the cost of bus and subway fares

Could you tell me which one is correct?

lowering the cost of bus and subway fares