Answer the following question given this paragraph: 

Alpha particles can travel only a few centimeters through air. They can burn the skin but not penetrate it. Beta particles can travel up to a meter through air. They can penetrate and damage skin. Gamma rays can travel thousands of meters through air. They can penetrate and damage cells deep inside the body.


Q: What kind of rays can travel thousands of meters through air and can penetrate and damage cells deep inside the body?

 Choices:

- x-rays

- cosmic rays

- plasma rays

- gamma rays

A:
gamma rays
