Question: who is the largest supermarket chain in the uk
[{'answer': 'Tesco'}, {'answer': 'Aldi'}, {'provenance': [{'wikipedia_id': '3048738', 'title': 'Tesco (disambiguation)', 'section': 'Section::::Abstract.', 'start_paragraph_id': 1, 'end_paragraph_id': 1, 'meta': {'evidence_span': ['Tesco PLC is an international retailer with headquarters in the United Kingdom.', 'Tesco PLC is an international retailer with headquarters in the United Kingdom.']}}]}, {'provenance': [{'wikipedia_id': '417553', 'title': 'John Sainsbury, Baron Sainsbury of Preston Candover', 'section': 'Section::::Business career.\n', 'start_paragraph_id': 14, 'end_paragraph_id': 14, 'meta': {'evidence_span': ["The Company also boasted the highest sales per square foot in the food retailing industry and the market share of the UK supermarket business increased from 2.5% to 10.4%. Sainsbury's also overtook both Tesco", "The Company also boasted the highest sales per square foot in the food retailing industry and the market share of the UK supermarket business increased from 2.5% to 10.4%. Sainsbury's also overtook both Tesco and Marks & Spencer (the latter shortly before his retirement on his 65th birthday on 2 November 1992) to become the UK's largest and most successful supermarket chain. Following his retirement, his cousin and Labour supporter David Sainsbury (now Lord Sainsbury of Turville) became Chairman. Tesco overtook Sainsbury's to become the UK's largest supermarket chain in 1995, and David Sainsbury stepped down as Chairman in 1998 to pursue his long held ambition to have a career in politics."]}}]}, {'provenance': [{'wikipedia_id': '98356', 'title': 'Tesco', 'section': 'Section::::History.:The lost years.\n', 'start_paragraph_id': 31, 'end_paragraph_id': 31, 'meta': {'evidence_span': ["Tesco being Britain's largest food retailer and Booker being the UK's largest wholesaler.", "its main supermarket business. On 27 January 2017, it was announced that Tesco had reached an agreement to merge with Britain's biggest wholesaler Booker Group to create the UK's largest food group, there are however concerns over market dominance with Tesco being Britain's largest food retailer and Booker being the UK's largest wholesaler. It was announced in March 2017 that Trevor Masters, International Chief Executive, would be leaving in May after 38 years with the company. On 1 April, Tony Hoggett became Tesco's CEO for Asia,"]}}]}]