Which is considered a chemical mutagen?
tanning beds
tobacco
x-rays
precious metals

Mutagens can be defined as the chemical or physical agents that have the capability to change the genetic material of an organism's DNA (Deoxyribonucleic acid) increasing the mutation in the population. The chemical mutagens are the chemical compounds which causes mutations in the genetic materials. The tobacco is considered as the chemical mutagen, it changes a person's DNA and leads to the formation of the cancer.

Hence, the answer is 'tobacco'.

the answer to your question is:

c. complementary base-pairing