This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Haematology, Subject name: Pathology
Prolonged prothrombin time is seen in ? 
Select and explain. 
A. Haemophilia A, B. Haemophilia B, C. Thrombocytopenia, D. Factor VII deficiency
D: Factor VII deficiency
Answer: D: Factor VII deficiency 
Explanation: Prothrombin time evaluates extrinsic factors and common pathway factors (factors 1,2,5,7,10).Prolongation of PT time occurs with deficiency of these factors. Haemophilia A is due to factor 8 deficiency, which is an intrinsic factor.So no PT prolongation Haemophilia B due to factor 9 deficiency. No PT Prolongation Thrombocytopenia due to decreased platelet number. so no PT prolongation . Factor 7 is an extrinsic factor .So its deficiency causes prolongation of PT Ref. Robbins and Cotran Pathologic basis of disease.South Asia Edition volume 1.page no.657,662,663 Harsh Mohan textbook of pathology 7th edition.Pg no.307