Question: the retinoid that has the most important physiological role in the human body is
[{'answer': 'Vitamin A', 'provenance': [{'wikipedia_id': '54114', 'title': 'Vitamin A', 'start_paragraph_id': 0, 'start_character': 0, 'end_paragraph_id': 0, 'end_character': 9, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '54114', 'title': 'Vitamin A', 'start_paragraph_id': 1, 'start_character': 0, 'end_paragraph_id': 1, 'end_character': 722, 'bleu_score': 0.9826823455989031, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 13592998729436090830}, 'section': 'Section::::Abstract.'}]}]