What is a common effect of an asymmetrically deployed spoiler on an aircraft?

When a spoiler is deployed asymmetrically on an aircraft, it disrupts the airflow over the wing on which it is deployed, leading to a change in the lift distribution. This alteration in lift can cause the aircraft to roll towards the side with the deployed spoiler because it reduces lift on that wing, effectively generating a banked attitude. The aircraft reacts by tilting into the direction where the lift has been decreased, resulting in a natural tendency for the aircraft to bank. This is utilized in flight maneuvers, particularly during turns and for managing lateral control.

The other options focus on aspects like vertical speed, overall drag, and lift efficiency, which do not directly capture the immediate and primary response of the aircraft to asymmetrical spoiler deployment. While those factors do play a role in the overall performance and aerodynamics of an aircraft, the immediate and perceptible effect of a spoiler deployed on one side is the change in banking attitude.