Mutations are usually induced by

The correct option is A Gamma rays
Mutations are usually induced by gamma rays. If a gamma ray hits a DNA strand, then it breaks the double strands of DNA. Normally, DNA can repair most radiation damage, but If there is a lot of damage, then the cell will not be able to divide properly and will die. Alpha, beta, and visible light can not induce mutations. Thus, the correct answer is option A.