Question: the most common type of rock in earth's crust is
[{'answer': 'igneous', 'provenance': [{'wikipedia_id': '199661', 'title': 'Rock (geology)', 'start_paragraph_id': 1, 'start_character': 246, 'end_paragraph_id': 1, 'end_character': 253, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '199661', 'title': 'Rock (geology)', 'start_paragraph_id': 15, 'start_character': 0, 'end_paragraph_id': 15, 'end_character': 677, 'bleu_score': 0.982060959997838, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 21905738720715797}, 'section': 'Section::::Classification.:Igneous rock.\n'}]}]