Which flight control does the left yoke operate when pulling the roll disconnect?

The left yoke's primary function includes the operation of the flight control surfaces responsible for rolling the aircraft, which are the ailerons. When the roll disconnect is pulled, the intention is to isolate the flight control systems related to roll and maintain control through other means.

The ailerons are the flight control surfaces that control the rolling motion of the aircraft, allowing the pilot to bank left or right. Therefore, when the roll disconnect is engaged, the left yoke retains its ability to manage the ailerons, ensuring that even with the roll disconnect in place, the pilot can still manipulate the aircraft's bank angle.

The multifunction spoilers primarily assist in roll control and can augment aileron movement, but they do not serve as the principal means of controlling roll when using the yoke. The right elevator and nosewheel steering pertain to pitch control and ground maneuvering, respectively, and do not relate directly to the roll control function of the left yoke. Thus, the answer concerning the left yoke's operation in regard to the roll disconnect pertains to its control of the ailerons.