Answer the following question given this paragraph: 

Genes are a major determinant of human skin color. However, exposure to ultraviolet radiation can increase the amount of pigment in the skin and make it appear darker.


Q: Exposure to what can increase the amount of pigment in the skin and make it appear darker?

 Choices:

- gamma rays

- sunlight

- nuclear radiation

- ultraviolet radiation

A:
ultraviolet radiation
