The client who has engaged in needle-sharing activities has developed a flu-like illness. An HIV antibody test is negative. Which statement best describes the scientific rationale for this finding?

A The client is fortunate not to have contracted HIV from an infected needle. C The client may be in the primary infection phase of an HIV infection. D The antibody test is negative because the client has a different flu virus. B The client must be repeatedly exposed to HIV before becoming infected.