Question: who began exploration of africa's atlantic coast
[{'answer': 'Henry Morton Stanley', 'provenance': [{'wikipedia_id': '2041178', 'title': 'European exploration of Africa', 'start_paragraph_id': 3, 'start_character': 789, 'end_paragraph_id': 3, 'end_character': 809, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '2041178', 'title': 'European exploration of Africa', 'start_paragraph_id': 59, 'start_character': 0, 'end_paragraph_id': 59, 'end_character': 479, 'bleu_score': 0.9277431284700741, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 11322070105483885493}, 'section': 'Section::::The 19th century.\n'}]}]