Drop-down Definition

dräpdoun
dropdown
adjective

Pull-down.

Webster's New World

Of a computer menu, opening downward to reveal a list of possible options.

Make your selection from the drop-down list.
Wiktionary
noun

(computing) A type of menu that, when selected, opens downward to reveal a list of possible options.

The choice you want should be somewhere in that drop-down.
Wiktionary