Question: where does the marc train stop in dc
[{'answer': 'Union Station', 'provenance': [{'wikipedia_id': '38412238', 'title': 'List of MARC Train stations', 'start_paragraph_id': 3, 'start_character': 391, 'end_paragraph_id': 3, 'end_character': 404, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}]