What type of suspension uses one lower control arm?

The MacPherson suspension is characterized by its use of a single lower control arm in conjunction with a strut assembly. This design simplifies the construction of the suspension system while allowing for effective control of the wheel's movement. The lower control arm provides support for the wheel as it responds to road conditions, while the strut acts to absorb shocks and maintain proper alignment. This makes the MacPherson suspension particularly popular in many modern vehicles due to its efficiency in terms of space and weight.

In contrast, other suspension types involve different configurations that either utilize more complexity or additional components. For example, multi-link suspension includes multiple arms to provide better wheel control and geometry. SLA (Short Long Arm) suspension typically features two control arms of varying lengths, and I-Beam suspension uses a rigid beam connecting the wheels. Therefore, the defining characteristic of the MacPherson suspension being a single lower control arm is what makes it the correct choice in this scenario.