Final answer:
The writer supports the statement that Africa is facing a health crisis using statistics on AIDS-related deaths and HIV prevalence in Africa, as well as the decline in average life expectancy.
Step-by-step explanation:
The writer supports the statement that Africa is facing the worst health crisis in human history by providing statistics on the number of Africans who have died from AIDS and the number of people living with HIV in Africa compared to the global total. Additionally, the writer mentions the average life expectancy drop in sub-Saharan Africa during the past two decades as another piece of evidence for the health crisis.