Answer the following question given this paragraph: 

Most Americans have plenty of fresh, clean water. But many people around the world do not. In fact, water scarcity is the world’s most serious resource problem. How can that be? Water is almost everywhere. But much of it is unusable. What is usable is not always where it is needed.


Q: What is the world’s most serious resource problem?

 Choices:

- gas shortage

- citrus blight

- deforestation

- water scarcity

A:
water scarcity
