Question: where does the heat from geothermal energy come from
[{'answer': 'radioactive decay of minerals', 'provenance': [{'wikipedia_id': '1251508', 'title': 'Geothermal heating', 'start_paragraph_id': 2, 'start_character': 118, 'end_paragraph_id': 2, 'end_character': 147, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'answer': 'solar energy absorbed at the surface'}, {'answer': 'heat retained within the Earth since the original formation of the planet'}, {'provenance': [{'wikipedia_id': '1251508', 'title': 'Geothermal heating', 'start_paragraph_id': 2, 'start_character': 0, 'end_paragraph_id': 2, 'end_character': 656, 'bleu_score': 0.929391499021567, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 17653420514066555372}, 'section': 'Section::::Abstract.'}]}]