Which step of a muscle contraction can be described as the shortest sacromere

Muscle activation is the process of activating the tension generating sites in the muscle fibers. The main events of the skeletal muscle contraction is divided into three stages which are: excitation of skeletal muscle fiber, excitation - contraction coupling and cross bridge cycling. The step of a muscle contraction that can be described as the shortest sacromere is STEP THREE.

A. mitochondrion b. nucleus