The correct option is A clotting factors
Blood clotting is a process in which blood platelets work together with the clotting factors to form a microscopic mesh on an open wound. This physically traps the RBCs from escaping and arrests bleeding.
In case of a haemophiliac patient, the clotting factors are absent, due to this the mesh formation (blood coagulation) takes a long time. Hence, a small cut can lead to excessive bleeding.