Most people who are exposed to the virus develop antibodies to hiv after the initial infection.

The answer to this question is "within 6 months". Most people who are exposed to the virus develop antibodies to HIV (stands for Human Immunodeficiency Virus) within 6 months after the initial infection. As per the study, once the person is being exposed develop antibodies that will protect him from getting infected by HIV or any other sexually transmitted diseases. 

You didn't give the options btw