Which of the following flight controls utilizes the hydraulic system?

The ailerons on the Embraer Regional Jet utilize the hydraulic system for their operation, which is essential for controlling the aircraft's roll during flight. Hydraulic systems provide the necessary force and responsiveness needed for the ailerons to move effectively, allowing pilots to adjust the aircraft's attitude and navigate through various flight conditions.

In modern aircraft like the Embraer Regional Jet, the integration of hydraulic systems with flight controls enhances the overall performance and reliability. The hydraulic power allows for quicker and more precise movements of the ailerons compared to mechanical systems, particularly during high-speed maneuvers.

While flaps, speed brakes, and slats may also be operated by hydraulic systems, they serve different functions related to lift and drag management, rather than directly controlling roll. This distinction highlights the unique role ailerons play in the aircraft's flight dynamics.