In the context of the input sentence, determine the relationship between 'grocery' and 'Walmart'.
Options: manufacturer, founded by, operator, subsidiary

And what we experienced was pure-play e-commerce omnichannel as well as people that were open, such as Walmart and Target, that sell groceries, or Costco, the brick-and-mortar guys that were open, and grocery as a whole channel more than picked up from that and the demand from our products, as I mentioned.
operator