Question: which city is hosting the 2017 mobile world congress (mwc)
[{'answer': 'Barcelona , Spain', 'provenance': [{'wikipedia_id': '12793425', 'title': 'Mobile World Congress', 'start_paragraph_id': 9, 'start_character': 31, 'end_paragraph_id': 9, 'end_character': 51, 'bleu_score': 1.0, 'section': 'Section::::History.:Event dates.\n'}]}, {'provenance': [{'wikipedia_id': '12793425', 'title': 'Mobile World Congress', 'start_paragraph_id': 6, 'start_character': 0, 'end_paragraph_id': 6, 'end_character': 314, 'bleu_score': 0.573613177901173, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 11404251288832724872}, 'section': 'Section::::History.\n'}]}]