Question: what caused the american oil crisis of 1974
[{'answer': 'an oil embargo', 'provenance': [{'wikipedia_id': '244180', 'title': '1973 oil crisis', 'start_paragraph_id': 1, 'start_character': 128, 'end_paragraph_id': 1, 'end_character': 142, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}]