Question: what is the main source of heat and light energy
[{'answer': 'Incandescence', 'provenance': [{'wikipedia_id': '4331300', 'title': 'List of light sources', 'start_paragraph_id': 2, 'start_character': 11, 'end_paragraph_id': 2, 'end_character': 24, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '4331300', 'title': 'List of light sources', 'start_paragraph_id': 3, 'start_character': 0, 'end_paragraph_id': 3, 'end_character': 85, 'bleu_score': 0.8781879837907131, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 5934696848013279787}, 'section': 'Section::::Incandescence.\n'}]}]