Question: what stimulates the corpus luteum to produce progesterone
[{'answer': 'Pregnenolone', 'provenance': [{'wikipedia_id': '528976', 'title': 'Corpus luteum', 'start_paragraph_id': 7, 'start_character': 179, 'end_paragraph_id': 7, 'end_character': 191, 'bleu_score': 1.0, 'section': 'Section::::Development and structure.\n'}]}, {'provenance': [{'wikipedia_id': '528976', 'title': 'Corpus luteum', 'start_paragraph_id': 7, 'start_character': 0, 'end_paragraph_id': 7, 'end_character': 536, 'bleu_score': 0.976043556018343, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 7572953032913839179}, 'section': 'Section::::Development and structure.\n'}]}]