Question: who played obi wan kenobi in star wars episode 3
[{'answer': 'Ewan McGregor', 'provenance': [{'wikipedia_id': '56196', 'title': 'Obi-Wan Kenobi', 'start_paragraph_id': 1, 'start_character': 258, 'end_paragraph_id': 1, 'end_character': 271, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}]