Which type of suspension employs upper and lower control arms connected to the steering knuckle by a ball joint?

The correct answer focuses on the SLA (short/long arm) suspension system, which is characterized by the use of both upper and lower control arms that connect to the steering knuckle via ball joints. This configuration allows for improved wheel movement and alignment, enhancing the vehicle's handling and ride quality. The design helps in separating the suspension movement from the steering mechanism, promoting better performance during cornering and providing a more stable ride.

In this type of suspension, the short arm typically serves to position the wheel and maintain camber during movement, while the longer arm aids in controlling the wheel's motion and providing better shock absorption. The presence of the ball joint at the intersection allows for the pivot needed for steering, while also permitting vertical wheel movement.

Other types of suspension systems mentioned do not fit this description. For example, the MacPherson strut suspension uses a single strut assembly to provide both spring and shock support, integrating the design in a different manner compared to the dual control arms that define the SLA system. Independent suspension, while a broader category that can include SLA, does not specifically refer to the use of upper and lower control arms. Leaf spring suspension predominantly relies on a different setup that does not involve control arms or ball joints for wheel positioning