Take a look at the sentence again:
We looked everywhere for the car keys—under the sofa cushions, __________,
and on the counters and tabletops. All along, Andrew had them in the front
pocket of his jeans!
The blank requires a prepositional phrase. You chose our search included the trash can, which is a main clause. You thus have a parallelism error. Before you continue, review the rules for parallel structure.
Go back to the sentence to try again.