This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Immunology, Subject name: Microbiology
Complement attaches to immunoglobulin at: 
Select and explain. 
A. Aminoterminal, B. Fab region, C. Variable region, D. Fc fragment
D: Fc fragment
Answer: D: Fc fragment 
Explanation: Ans. is 'd' i.e., Fc fragment (Ref: Ananthanarayan, 8th/e, p. 97)* Fc fragment consist of parts of both H chains, composed of carboxyterminal portion of the H chains and it determines biological properties of Ig molecule such as complement fixation, placental transfer, skin fixation and catabolic rate.