Question: who plays mark usher on house of cards
[{'answer': 'Campbell Scott', 'provenance': [{'wikipedia_id': '48838609', 'title': 'List of House of Cards characters', 'start_paragraph_id': 30, 'start_character': 24, 'end_paragraph_id': 30, 'end_character': 38, 'bleu_score': 1.0, 'section': 'Section::::Main characters.\n'}]}]