The following are statements regarding the role of different substances in the process of blood clotting. 
P. Prothrombin is a key protein involved in the coagulation cascade.
Q. Sodium acts as a cofactor for various enzymes involved in coagulation 
R. Fibrinogen is a soluble protein found in the blood that is converted into fibrin during blood clotting 
S. Vitamin K is essential for the synthesis of several blood clotting factors in the liver.
Which of the following options includes all the correct statements?

• A. P, Q, and R
• B. Q, R, and S
• C. P, R, and S
• D. P, Q, R, and S

Answer: (C)