Answer:
Skeletal muscle
Step-by-step explanation:
Skeletal muscle refers to the muscles that are attached to our bones. These muscles were attached by a collection of collagen fibers which most commonly known tendons. We can move the vast majority of these muscles voluntarily
The act of bending and straightening the elbow like Jack did is being done by using the combination of biceps and triceps muscle that are attached to the skeletal structure of your arm.