Question: cytosine is an example of a nitrogen base found on what acids
[{'answer': 'nucleic', 'provenance': [{'wikipedia_id': '1393654', 'title': 'Nitrogenous base', 'start_paragraph_id': 1, 'start_character': 199, 'end_paragraph_id': 1, 'end_character': 206, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '1393654', 'title': 'Nitrogenous base', 'start_paragraph_id': 4, 'start_character': 0, 'end_paragraph_id': 4, 'end_character': 975, 'bleu_score': 0.7797491971080791, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 5051167104939489224}, 'section': 'Section::::Role in nucleic acids.\n'}]}]