Analyze the relationship between 'grocery' and 'Walmart' within the context of the input sentence.
Options: member of, operator, subsidiary, platform

Reddit Email Print Reprint NEW YORK ( TheStreet ) --  Walmart ( WMT - Get Report ) stock is increasing by 0.42% to $63.93 in mid-morning trading on Tuesday, after the company announced it will expand a service that allows customers to pick up their online grocery orders from store parking lots.
operator