Question

Contractile proteins are found in _____.
A. Bones
B. Blood
C. Muscles
D. Cartilage

Answer 1

Tropomyosins, along with the other proteins actin and myosin, are contractile proteins that control contraction in muscle and nonmuscle cells and are everywhere in animal cells.

Complete answer:
Proteins which mediate sliding of contractile (contraction) fibre of the cell cytoskeleton and of the heart and skeletal muscle are contractile proteins. Heart and muscle contractile fibres are bundles of actin polymers that move together with each other by the motor protein myosin and the related contractile proteins like troponin and titin.
Collagen is the bone matrix's main structural part. Collagen is a fibrous and rope-like protein.
Two forms of protein in our body are albumin and globulin. The total protein test measures our body's total amount of albumin and globulin.
Contractile proteins are muscle contraction power generators. These proteins are required in voluntarily moving muscles. Contractile proteins are of two types. They are myosin and actin. These proteins contribute to muscular contraction and thus to movement. The muscles and not bones, blood and cartilage need the movement.
Cartilage is a connective tissue, a connective tissue. It's strong and flexible. Chondroblast creates an extracellular matrix rich in proteins, is considered the advanced cell of cartilage. Chondroblast is termed as chondrocytes which are trapped in the matrix.

Thus, the correct answer is option C. i.e., Muscles.

Note: Bones and cartilage have collagen protein that stimulates the growth in cartilage and provides strength and structure to the bones. Collagen is also present in tendons and muscle skin. It holds the body together.