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

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