This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Medicine
True about blood transfusion -a) Antigen `D' determines Rh positivityb) Febrile reaction is due to HLA antibodiesc) Anti-D is naturally occuring antibodyd) Cryoprecipitate contains all coagulation factors 
Select and explain. 
A. ac, B. a, C. ab, D. bc
C: ab
Answer: C: ab 
Explanation: None