Which one of the following viruses causes post-transfusion hepatitis?

Correct option is C

Hepatitis C is the most common cause of post-transfusion hepatitis, especially before screening of blood products became routine. Explanation of each option: • (a) Hepatitis A – Spread by fecal-oral route, not blood. It does not cause post-transfusion hepatitis. • (b) Hepatitis B – Can be transmitted via blood, but with current vaccination and screening, its risk via transfusion is lower than Hepatitis C. • (c) Hepatitis C – Correct. A major cause of transfusion-associated hepatitis, especially before 1992 when routine screening started. • (d) Hepatitis D – Requires co-infection with Hepatitis B; not typically transmitted via transfusion alone.