Question: who portrayed the president of the united states in the alien invasion comedy mars attacks
[{'answer': 'Jack Nicholson', 'provenance': [{'wikipedia_id': '3565461', 'title': 'Mars Attacks!', 'start_paragraph_id': 1, 'start_character': 291, 'end_paragraph_id': 1, 'end_character': 305, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}]