15. Which of the following statements about blood clotting is true? (A) Threads of fibrin trap blood cells and platelets. (B) Fibrin is enzymatically converted to fibrinogen.  (C) During the clotting response, platelets rapidly congregate in the interstitial fluid. (D) The first response to an injury is dilation of the damaged blood vessels. (E) Chemicals released by platelets prevent cell division in smooth muscle and connective tissues.