Question: what's the tallest roller coaster in the us
[{'answer': 'Kingda Ka', 'provenance': [{'wikipedia_id': '2533444', 'title': 'List of roller coaster rankings', 'start_paragraph_id': 2, 'start_character': 606, 'end_paragraph_id': 2, 'end_character': 615, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}]