Question: who proposed the first comprehensive theory of continental drift
[{'answer': 'Alfred Wegener', 'provenance': [{'wikipedia_id': '6056', 'title': 'Continental drift', 'start_paragraph_id': 1, 'start_character': 331, 'end_paragraph_id': 1, 'end_character': 345, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '6056', 'title': 'Continental drift', 'start_paragraph_id': 1, 'start_character': 90, 'end_paragraph_id': 1, 'end_character': 653, 'bleu_score': 0.6805648866696451, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 12890945586039739083}, 'section': 'Section::::Abstract.'}]}]