给问句选择合适的应答语。

How do we save water?            A. He's drinking water.

Where does water come from?             B. We use water to grow crops.

What do you want to be?             C. We can turn off the tap when we don't use water.

How do we use water?             D. It comes from the sea.

What is he doing?             E. I want to be a fireman.