Final answer:
The range of motion is greatest during passive stretching because the muscles are not actively contracting, allowing for an increase in movement without muscle tension restricting it.
Step-by-step explanation:
Range of motion is highest with d) Passive stretching as muscles are not being actively contracted. Unlike isometric contractions, where muscle tension increases but the muscle length remains the same, or isotropic contractions which include both concentric and eccentric contractions where muscle length changes to move a load, passive stretching involves no active contraction of the muscles. During passive stretching, another force, either an external object (like a stretching device) or another part of the body, is used to stretch the muscle, which allows for an increase in range of motion as there is no muscle tension working against the movement.