Question: red colour of ruby crystal is due to
[{'answer': 'the element chromium', 'provenance': [{'wikipedia_id': '43551', 'title': 'Ruby', 'start_paragraph_id': 1, 'start_character': 346, 'end_paragraph_id': 1, 'end_character': 366, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '43551', 'title': 'Ruby', 'start_paragraph_id': 1, 'start_character': 0, 'end_paragraph_id': 1, 'end_character': 366, 'bleu_score': 0.9679895851501501, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 12740135343355656168}, 'section': 'Section::::Abstract.'}]}]