Question: who was president of united states in april 1975
[{'answer': 'Ford', 'provenance': [{'wikipedia_id': '5030380', 'title': 'Gerald Ford', 'start_paragraph_id': 0, 'start_character': 7, 'end_paragraph_id': 0, 'end_character': 11, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '5030380', 'title': 'Gerald Ford', 'start_paragraph_id': 105, 'start_character': 0, 'end_paragraph_id': 105, 'end_character': 676, 'bleu_score': 0.982060959997838, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 2179680197041093668}, 'section': 'Section::::Presidency (1974–1977).:Foreign policy.:Vietnam.\n'}]}]