Question: what is the largest nuclear bomb america has
[{'answer': 'Mk / B53', 'provenance': [{'wikipedia_id': '1124920', 'title': 'B53 nuclear bomb', 'start_paragraph_id': 1, 'start_character': 4, 'end_paragraph_id': 1, 'end_character': 14, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '1124920', 'title': 'B53 nuclear bomb', 'start_paragraph_id': 1, 'start_character': 0, 'end_paragraph_id': 1, 'end_character': 305, 'bleu_score': 0.9632870032952191, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 12861266325365090933}, 'section': 'Section::::Abstract.'}]}]