A Study of the Occupational Exposure to HIV Among Health

A study of the occupational exposure to HIV among health care workers recruited 33 health care workers who had become HIV-seropositive after exposure to HIV at work and 665 health care workers who had been exposed to HIV but had not become seropositive. The study found that contaminated health care workers were more likely to have been exposed to large amounts of blood and less likely to have taken the drug AZT immediately after exposure than those who had not become seropositive.
What is the population in this study?

A) All health care workers who became HIV-seropositive after exposure to HIV at work
B) All health care workers who were exposed to HIV at work
C) All health care workers who are HIV-seropositive
D) Only the 698 health care workers interviewed