The correct option is D Enterokinase
Enterokinase is an enzyme produced by cells of the duodenum and involved in human and animal digestion. It is secreted from intestinal glands following the entry of ingested food passing from the stomach. Enterokinase is a specific protease that cleaves after lysine at its cleavage site Asp-Asp-Asp-Asp-Lys. It will sometimes cleave at other basic residues, depending on the conformation of the protein substrate.