This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: G.I.T., Subject name: Medicine
Budd - Chiari Syndrome occurs in: 
Select and explain. 
A. Antithrombin deficiency, B. Protein C deficiency, C. Oral contraceptive use, D. All of the above
D: All of the above
Answer: D: All of the above 
Explanation: (All of the above) (336, 627, 1862, 1874-H 16th) (612-13-CMDT-09) (362, 661, 733,1945, 1990-Hl7th)BUDD-CHIAR1 SYNDROME (Hepatic vein obstruction)* Many cases associated with polycythemia vera or other proliferative diseases* Predisposition to thrombosis (e.g. - hyperprothrombinemia) factor II G20210 A mutation) activated protein C resistance (Factor V Leiden mutation) Protein C or S or antithrombin deficiency, the methylenetetrahydro folate reductase mutation, antiphospholipid antibodies can be identified.* Right sided heart failure or constrictive pericarditis, neoplasm.* Paroxysmal nocturnal hemoglobinuria, Behcet's syndrome blunt abdominal trauma, use of oral contraceptives and pregnancy.* Cytotoxic agents and pyrrolizidine alkaloids ("bush teas")The screening test of choice is colour or pulsed Doppler ultrasonography