In the simplest wireless LAN configuration, all devices equipped with a client adapter can communicate directly with one another. Which term describes this configuration?

Ad Hoc.

Explanation:

In the simplest wireless LAN configuration, all devices equipped with a client adapter can communicate directly with one another. The term which best describes this configuration is an Ad hoc.

This ultimately implies that, an Ad hoc connection is a configuration mode which makes it possible for devices that are equipped with a client adapter such as a computer, to communicate (send and receive data) directly with one another without the intervention of any intermediary device such as a router, hub etc.