The correct option is
C Dextrin
Keratin is a family of fibrous structural proteins. It is the protein that protects epithelial cells from damage or stress that has potential to kill the cell.
Elastin is a highly elastic protein in connective tissue and allows many tissues in the body to resume their shape after stretching or contracting.
Dextrins are a group of low-molecular-weight carbohydrates produced by the hydrolysis of starch or glycogen.
Collagen is the main structural protein in the extracellular space in the various connective tissues in animals.
As Dextrin is a carbohydrate, whereas rest others are proteins, hence it is unrelated.
Hence, option C is correct.