Question: who plays howard stark in iron man 2
[{'answer': 'John Slattery', 'provenance': [{'wikipedia_id': '22144721', 'title': 'Iron Man 2', 'start_paragraph_id': 18, 'start_character': 235, 'end_paragraph_id': 18, 'end_character': 248, 'bleu_score': 1.0, 'section': 'Section::::Cast.\n'}]}, {'provenance': [{'wikipedia_id': '22144721', 'title': 'Iron Man 2', 'start_paragraph_id': 18, 'start_character': 0, 'end_paragraph_id': 18, 'end_character': 840, 'bleu_score': 0.887114664598565, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 11777793360771497473}, 'section': 'Section::::Cast.\n'}]}]