Which of the following is the most abundant protein in animals?

The correct option is B Collagen
Collagen protein is the most abundant protein in the animal world. Collagen is a helical fibrous protein found mainly in the connective tissues. It provides mechanical strength and stability to tissues such as tendons, ligaments, skin, etc.

Keratin is also a fibrous protein produced in some epithelial cells of vertebrates. This protein acts as the structural protein in hair, nails, horn, hoofs, feathers, etc.

Haemoglobin is a globular protein found in RBCs and is responsible for gaseous transport in the body. It gives blood its red colour.

Actin is a contractile protein predominantly present in the muscle cells.