Question: who played dumbledore in harry potter and the half blood prince
[{'answer': 'Michael Gambon', 'provenance': [{'wikipedia_id': '858575', 'title': 'Harry Potter and the Half-Blood Prince (film)', 'start_paragraph_id': 82, 'start_character': 260, 'end_paragraph_id': 82, 'end_character': 274, 'bleu_score': 1.0, 'section': 'Section::::Reception.:Critical response.\n'}]}]