Question: what is the closest airport to white sulphur springs west virginia
[{'answer': 'Greenbrier Valley Airport', 'provenance': [{'wikipedia_id': '2448214', 'title': 'Greenbrier Valley Airport', 'start_paragraph_id': 0, 'start_character': 0, 'end_paragraph_id': 0, 'end_character': 25, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}]