Question: what is contained in the nucleus of an atom
[{'answer': 'protons and neutrons', 'provenance': [{'wikipedia_id': '19916559', 'title': 'Atomic nucleus', 'start_paragraph_id': 1, 'start_character': 60, 'end_paragraph_id': 1, 'end_character': 80, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '19916559', 'title': 'Atomic nucleus', 'start_paragraph_id': 1, 'start_character': 0, 'end_paragraph_id': 1, 'end_character': 713, 'bleu_score': 0.9832621206481431, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 16393763507940450180}, 'section': 'Section::::Abstract.'}]}]