Question: which country has the highest hiv in africa
[{'answer': 'South Africa', 'provenance': [{'wikipedia_id': '2705217', 'title': 'List of countries by HIV/AIDS adult prevalence rate', 'start_paragraph_id': 4, 'start_character': 21, 'end_paragraph_id': 4, 'end_character': 33, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}]