What can cause hard steering in a vehicle?

Hard steering in a vehicle can indeed be caused by low power steering fluid, a malfunctioning pump, or binding in the steering linkage.

When the power steering fluid is low, there isn't enough hydraulic assistance available to help the driver turn the steering wheel, resulting in increased effort required to steer the vehicle. Additionally, a malfunctioning power steering pump can fail to provide the necessary pressure, leading to similar difficulties in steering. Lastly, binding in the steering linkage—such as in the tie rods or the steering column—can create resistance against the natural movement of the steering system, causing the steering to feel heavy and unresponsive.

The other options are less directly related to the steering feel. For instance, excessively high tire pressure can affect tire wear and handling, but does not typically create a problem with the steering mechanism itself. New tires that haven't seated properly may create unusual driving characteristics but are unlikely to cause consistently hard steering. Worn-out brake pads can lead to decreased braking performance but would not inherently affect the effort needed to steer the vehicle.

So, option A encompasses the primary mechanical issues related to the steering system that can result in hard steering, making it the most accurate answer.