4. Natural gas is cheaper fuel than diesel, but it has higher capital cost and what does this mean?

The cost of modifying tanks and engines in cars, changing fuel stations,

Explanation:

Natural gas has a higher cost because cars will need to have their engines and tanks modified to be able to use natural gas or people will have to buy a new one. Also, fuel stations will need to be changed or new ones will have o be built which is a expensive infrastructure.