Which sentence correctly uses the past perfect tense? Carl bought a ticket three weeks in advance. Carl will have lost his map by the end of the trip. Carl has packed three suitcases for his trip. Carl had asked his mother's permission before he left town.

A Past Perfect Tense indicates actions that have been accomplished or done in the past before another action takes place. In the choices given, the example of the sentence that uses past perfect tense is, "Carl had asked his mother's permission before he left town."