Question: how many episodes are there in season 1 of the killing
[{'answer': '13', 'provenance': [{'wikipedia_id': '31075273', 'title': 'List of The Killing episodes', 'start_paragraph_id': 2, 'start_character': 19, 'end_paragraph_id': 2, 'end_character': 21, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}]