- hepatitis C
- strep throat
- cytomegalovirus infection
- Pneumocystis jiroveci pneumonia
Number 4 is correct.
Rationale: Pneumocystis jiroveci pneumonia is the most common opportunistic infection in children with HIV. Hepatitis C and strep throat are not commonly opportunistic infections limited to children with HIV. Although cytomegalovirus may be present in HIV, it is not the most common opportunistic infection.