Which of the following is a common symptom of HIV/AIDS?

Diarrhea lasting more than one week is a well-documented symptom associated with HIV/AIDS. This condition can arise from the illness itself or as a side effect of opportunistic infections that often occur in individuals with a compromised immune system due to HIV. Persistent diarrhea can lead to dehydration and nutritional deficiencies, making it a significant concern in the context of HIV/AIDS.

The other options do not align with common symptoms associated with HIV/AIDS. Strong hair growth, constant headaches, and increased energy are not typical indicators of the disease and may reflect other health issues or conditions unrelated to HIV/AIDS. In the context of understanding HIV/AIDS symptoms, diarrhea is a recognized indicator that helps in identifying and managing the progression of the infection in patients.