Take a look at the passage again:
James opened the door of his cluttered refrigerator. Which caused a pint
of blueberries to fall to the floor. The fruit
bounced and rolled everywhere in an explosion of indigo.
You chose the third part, The fruit bounced and rolled everywhere in an explosion of indigo. This part has a main clause: Fruit is the subject; bounced and rolled are the verbs. A fragment will not have a main clause.
Go back to the passage to try again.