This exercise is testing the difference between the relative pronouns qui and que. Qui is used on the subject of a sentence: that is, the thing or person doing the action. Who stole the bag? The man, therefore:L’homme qui a volé mon sac s’est échappé. Que is used on the object of a sentence: that is, the person/thing being acted on. Who saw the jumper? Me, so I am the subject and the jumper is the object, therefore:Le pull que j’ai vu a été acheté par un autre client.