Question: which african american led the back to africa movement during the early 20th century
[{'answer': 'Marcus Garvey', 'provenance': [{'wikipedia_id': '8311688', 'title': 'Back-to-Africa movement', 'start_paragraph_id': 22, 'start_character': 311, 'end_paragraph_id': 22, 'end_character': 324, 'bleu_score': 1.0, 'section': 'Section::::United States.:Post-Emancipation.\n'}]}, {'provenance': [{'wikipedia_id': '8311688', 'title': 'Back-to-Africa movement', 'start_paragraph_id': 22, 'start_character': 19, 'end_paragraph_id': 22, 'end_character': 504, 'bleu_score': 0.784415780649472, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 11906148184342442801}, 'section': 'Section::::United States.:Post-Emancipation.\n'}]}]