What is true regarding the mechanical advantage of a single pulley?

A single pulley does not provide mechanical advantage in the sense that it does not reduce the amount of input force required to lift a load; it simply changes the direction of the force applied. When you use a single pulley, the effort needed to lift the load remains equal to the weight of the load itself. This means that while it can be helpful for changing the direction of the force—for instance, allowing a person to pull down to lift an object up—it does not make it easier to lift heavier loads.

In contrast, if a system includes multiple pulleys, it can create a mechanical advantage where less force is needed to lift heavier weights. Therefore, while single pulleys have their uses in providing control and directionality to lifting tasks, they do not decrease the effort required to lift a load. This is why "It does not provide mechanical advantage" is the correct understanding in this context.