Question: the extraembryonic membrane that helps in the formation of the placenta is the
[{'answer': 'chorion', 'provenance': [{'wikipedia_id': '326639', 'title': 'Chorion', 'start_paragraph_id': 1, 'start_character': 4, 'end_paragraph_id': 1, 'end_character': 11, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '326639', 'title': 'Chorion', 'start_paragraph_id': 1, 'start_character': 0, 'end_paragraph_id': 1, 'end_character': 337, 'bleu_score': 0.795865067578519, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 3465799117163435154}, 'section': 'Section::::Abstract.'}]}]