Here's a problem to solve: Some of the new cars being made can run on a renewable fuel that is made mostly from corn. Scientists are developing even more renewable fuels to replace gasoline. Why are renewable fuels most likely becoming more important?

Among the 4 following options, which is the correct answer?

- A: Renewable fuels release less energy.
 
- B: Car fuel tanks are being made smaller.
 
- C: The demand for gasoline is decreasing.
 
- D: Nonrenewable fuel supplies are limited.
 