Question: what is the name of the principal stock exchange in the united kingdom (i.e. england)
[{'answer': 'The London Stock Exchange', 'provenance': [{'wikipedia_id': '8542557', 'title': 'List of European stock exchanges', 'start_paragraph_id': 4, 'start_character': 86, 'end_paragraph_id': 4, 'end_character': 111, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}]