Question: who is thanos in avengers age of ultron
[{'answer': 'Josh Brolin', 'provenance': [{'wikipedia_id': '701741', 'title': 'Thanos', 'start_paragraph_id': 2, 'start_character': 117, 'end_paragraph_id': 2, 'end_character': 128, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}]