Which of the following statements is true?
a) As long as they continue to take HIV medicine as prescribed, an HIV-positive person can remain healthy.
b) HIV is the illness that follows once AIDS has weakened the person's immune system so that it cannot fight off infection.
c) Just as the body can rid itself of many different viruses, the human body can rid itself of HIV if a person is relatively healthy.
d) There are currently no effective medications that control HIV or help to reduce the risk of transmission.