Which characteristic of a vehicle's handling may be affected by worn suspension parts?

Worn suspension parts play a critical role in a vehicle's handling, and steering response is particularly affected by their condition. The suspension system is responsible for supporting the weight of the vehicle and absorbing shocks from the road, which directly influences how the wheels make contact with the surface.

When suspension components, such as struts, shocks, or bushings, are worn, they can lead to reduced stability and control. This results in less precise steering, causing the vehicle to feel loose or unresponsive during maneuvers. A lack of responsiveness can create difficulties in steering, such as excessive play in the steering wheel or delayed reaction to inputs, which can compromise safety and driving comfort.

In contrast, other aspects like engine efficiency, transmission performance, and brake effectiveness are more directly influenced by their respective systems. While these parts contribute to the overall operation of the vehicle, they are not primarily affected by the condition of the suspension. Thus, the correct choice that highlights the impact of worn suspension on vehicle handling is steering response.