If a vehicle has a worn tie rod end on the left rear, which of the following would be impacted?

Having a worn tie rod end on the left rear of a vehicle would primarily impact the rear toe alignment. The tie rod end is a critical component of the steering and suspension system, connecting the steering mechanism to the wheel assembly. When it becomes worn, it can lead to improper alignment of the rear wheels, particularly affecting the toe setting, which is the angle of the wheels in relation to each other when viewed from above.

Alterations in rear toe can cause uneven tire wear, affect handling, and impact vehicle stability. The other alignment parameters such as rear camber, front toe, and front caster are influenced to a lesser extent by a malfunctioning rear tie rod end, as these angles are typically adjusted based on different geometries and components in the suspension system. Thus, the most direct consequence of a worn left rear tie rod end would indeed be on rear toe.