Which of the following is a sign of the AIDS stage of HIV infection?

In the context of HIV infection, the AIDS stage is characterized by a significantly compromised immune system, which predisposes individuals to opportunistic infections. These infections are caused by organisms that typically do not cause disease in individuals with healthy immune systems but can be life-threatening for those with AIDS. Examples include pneumonia caused by Pneumocystis jirovecii, candidiasis, and various types of tuberculosis.

High fever, skin rashes, and mild cough may be associated with different stages of HIV infection or other illnesses, but they are not definitive indicators of the AIDS stage. Opportunistic infections serve as a clear marker of the progression to AIDS, as they suggest that the immune system is severely weakened and unable to defend the body against pathogens that it usually would handle effectively.