Answer the following question given this paragraph: 

Most ecosystems get their energy from the Sun. Only producers can use sunlight to make usable energy. Producers convert the sunlight into chemical energy or food. Consumers get some of that energy when they eat producers. They also pass some of the energy on to other consumers when they are eaten. In this way, energy flows from one living thing to another.


Q: Where do most ecosystems get their energy from?

 Choices:

- earth

- heat

- water

- sun

A:
sun
