Question: a nerve impulse triggers the release of what chemical at a neuromuscular junction
[{'answer': 'Acetylcholine', 'provenance': [{'wikipedia_id': '681908', 'title': 'Neuromuscular junction', 'start_paragraph_id': 10, 'start_character': 11, 'end_paragraph_id': 10, 'end_character': 24, 'bleu_score': 1.0, 'section': 'Section::::Structure and function.:Quantal transmission.\n'}]}]