Question: the hormone that the pineal gland secretes is
[{'answer': 'melatonin', 'provenance': [{'wikipedia_id': '285152', 'title': 'Pineal gland', 'start_paragraph_id': 1, 'start_character': 137, 'end_paragraph_id': 1, 'end_character': 146, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '285152', 'title': 'Pineal gland', 'start_paragraph_id': 1, 'start_character': 0, 'end_paragraph_id': 1, 'end_character': 495, 'bleu_score': 0.8381950208898411, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 7845449232992400660}, 'section': 'Section::::Abstract.'}]}]