This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Cardiovascular system, Subject name: Physiology
Which of the following helps in bridging the fibrin in a clot and stabilizes the clot? 
Select and explain. 
A. Factor XIII, B. Factor V, C. Factor VII, D. Factor III
A: Factor XIII
Answer: A: Factor XIII 
Explanation: The fibrin is initially a loose mesh of interlacing strands. It is conveed by the formation of covalent cross-linkages to a dense, tight aggregate (stabilization). This latter reaction is catalyzed by activated factor XIII and requires Ca2+.Factor V is required for formation of prothrombin activatorFactoVII is required for the activation of factor XFactor III is also required for formation of prothrombin activatorRef: Ganong's Review of Medical Physiology Twenty-Third Edition Page No:532