Question: who led the first expedition to reach asia by sailing west across the pacific ocean
[{'answer': 'Vasco da Gama', 'provenance': [{'wikipedia_id': '6646612', 'title': 'Chronology of European exploration of Asia', 'start_paragraph_id': 45, 'start_character': 38, 'end_paragraph_id': 45, 'end_character': 51, 'bleu_score': 1.0, 'section': 'Section::::Second wave of exploration (by sea).\n'}]}, {'provenance': [{'wikipedia_id': '6646612', 'title': 'Chronology of European exploration of Asia', 'start_paragraph_id': 45, 'start_character': 0, 'end_paragraph_id': 45, 'end_character': 172, 'bleu_score': 0.9243880458347601, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 3848629610532139049}, 'section': 'Section::::Second wave of exploration (by sea).\n'}]}]