Question: what are the four types of soil erosion
[{'answer': 'splash erosion', 'provenance': [{'wikipedia_id': '59416', 'title': 'Soil erosion', 'start_paragraph_id': 7, 'start_character': 108, 'end_paragraph_id': 7, 'end_character': 122, 'bleu_score': 1.0, 'section': 'Section::::Physical processes.:Rainfall and surface runoff.\n'}]}, {'answer': 'sheet erosion', 'provenance': [{'wikipedia_id': '59416', 'title': 'Soil erosion', 'start_paragraph_id': 7, 'start_character': 126, 'end_paragraph_id': 7, 'end_character': 139, 'bleu_score': 1.0, 'section': 'Section::::Physical processes.:Rainfall and surface runoff.\n'}]}, {'answer': 'rill erosion', 'provenance': [{'wikipedia_id': '59416', 'title': 'Soil erosion', 'start_paragraph_id': 7, 'start_character': 143, 'end_paragraph_id': 7, 'end_character': 155, 'bleu_score': 1.0, 'section': 'Section::::Physical processes.:Rainfall and surface runoff.\n'}]}, {'answer': 'gully erosion', 'provenance': [{'wikipedia_id': '59416', 'title': 'Soil erosion', 'start_paragraph_id': 7, 'start_character': 163, 'end_paragraph_id': 7, 'end_character': 176, 'bleu_score': 1.0, 'section': 'Section::::Physical processes.:Rainfall and surface runoff.\n'}]}, {'provenance': [{'wikipedia_id': '59416', 'title': 'Soil erosion', 'start_paragraph_id': 7, 'start_character': 0, 'end_paragraph_id': 7, 'end_character': 385, 'bleu_score': 0.9679895851501501, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 16699947940319924870}, 'section': 'Section::::Physical processes.:Rainfall and surface runoff.\n'}]}]