Which of the following is an agent that can induce mutations in DNA?

A mutagen is a specific type of agent that can induce changes or mutations in DNA sequences. These changes can occur in different ways, such as by directly affecting the structure of DNA, causing replication errors, or interacting with the cellular machinery involved in DNA repair. In essence, mutagens are responsible for increasing the frequency of mutations beyond the normal background levels.

While carcinogens and teratogens can indeed influence genetic material, their definitions and primary effects differ. Carcinogens specifically initiate or promote cancer by causing mutations that lead to uncontrolled cell growth, whereas teratogens are substances that cause developmental malformations during embryonic growth, not directly inducing mutations in the DNA itself. An antigen, on the other hand, is a substance that triggers an immune response and does not involve changes in DNA. Thus, the defining characteristic of a mutagen is its direct role in modifying genetic information, which makes it the correct choice in this context.