Question: who won the wwe championship elimination chamber 2018
[{'answer': 'Roman Reigns', 'provenance': [{'wikipedia_id': '55948000', 'title': 'Elimination Chamber (2018)', 'start_paragraph_id': 2, 'start_character': 91, 'end_paragraph_id': 2, 'end_character': 103, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '55948000', 'title': 'Elimination Chamber (2018)', 'start_paragraph_id': 2, 'start_character': 0, 'end_paragraph_id': 2, 'end_character': 777, 'bleu_score': 0.964583525681703, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 17963874762761517388}, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '55948000', 'title': 'Elimination Chamber (2018)', 'start_paragraph_id': 0, 'start_character': 0, 'end_paragraph_id': 0, 'end_character': 0, 'bleu_score': 1.0, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 17963874762761517388}, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '55948000', 'title': 'Elimination Chamber (2018)', 'section': 'Section::::Abstract.', 'start_paragraph_id': 2, 'end_paragraph_id': 2, 'meta': {'evidence_span': ['In the main event, Roman Reigns won the first-ever seven-man Elimination Chamber match to become the number one contender against Brock Lesnar for the Universal Championship at WrestleMania 34.', 'Roman Reigns won the first-ever seven-man Elimination Chamber match to become the number one contender against Brock Lesnar for the Universal Championship at WrestleMania 34.', 'Six matches were contested at the event, including one on the pre-show. In the main event, Roman Reigns won the first-ever seven-man Elimination Chamber match to become the number one contender against Brock Lesnar for the Universal Championship at WrestleMania 34']}}]}]