What is the relationship between grocery and Walmart in the context of the input sentence. Choose an answer from: product/material produced; manufacturer; distributed by; industry; position held; original broadcaster; owned by; founded by; distribution format; headquarters location; stock exchange; currency; parent organization; chief executive officer; director/manager; owner of; operator; member of; employer; chairperson; platform; subsidiary; legal form; publisher; developer; brand; business division; location of formation; creator.

"Meanwhile, as competitors like Kroger, Publix, H-E-B, Jewel-Osco and others have invested in evolving customer lifestyle trends – by broadening organic and fresh offerings – and in improving customer service, the gap between both comp-store sales growth and customer satisfaction at Walmart U.S. grocery and supermarket competitors continues to widen," Hood wrote in a note to clients Monday.

Answer: operator