Answer the following question given this paragraph: 

Every split second that sunlight hits that leaf, photosynthesis is initiated, bringing energy into the ecosystem. It could be said that this is one of the most important - if not the absolutely most important - biochemical reactions. And it all starts with the leaf.


Q: Photosynthesis is initiated by what hitting plants?

 Choices:

- dirt

- air

- moisture

- sunlight

A:
sunlight
