Text: When those same shoppers shop at a department store, they have no way of knowing that it has sold all of its fleece-lined garage booties or Scotchgard triple-stitched Velcro workboots unless they ask a clerk or keep notes from previous visits.
Entailment: When people shop at a big store, they don't know if it sold all of something.
Contradiction: When people shop at a big store, they know if it sold all of something.