Question: who was the voice of rocket on guardians of the galaxy
[{'answer': 'Bradley Cooper', 'provenance': [{'wikipedia_id': '2753418', 'title': 'Rocket Raccoon', 'start_paragraph_id': 2, 'start_character': 343, 'end_paragraph_id': 2, 'end_character': 357, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}]