Question: what do you call rocks that form when flowing lava solidifies
[{'answer': 'lava', 'provenance': [{'wikipedia_id': '21438242', 'title': 'Lava', 'start_paragraph_id': 1, 'start_character': 252, 'end_paragraph_id': 1, 'end_character': 256, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}]