Question: what is the fourth letter of the greek alphabet
[{'answer': 'delta', 'provenance': [{'wikipedia_id': '715909', 'title': 'Greek alphabet', 'start_paragraph_id': 94, 'start_character': 23, 'end_paragraph_id': 94, 'end_character': 28, 'bleu_score': 1.0, 'section': 'Section::::Glyph variants.\n'}]}]