<prompt> True about Haemophilia A are all exceptPTT increasedPT increasedClotting time is increasedSerum levels of factor VIII are decreased  <response>: Answer is B PT is increased: It is PTT which is affected increased and not PT unaffected. Haemophilia A occurs due to deficiency or reduced activity of factor VIII antihaemophilic factor. Factor VIII is involved in the intrinsic pathway which is measured by PTT and not in extrinsic pathway which is measured as PT. 