This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Cells and Tissues of Immune System, Subject name: Pathology
Complement proteins constitute what percentage of serum proteins? 
Select and explain. 
A. <1, B. 5-Jan, C. 5-10%, D. >10%
C: 5-10%
Answer: C: 5-10% 
Explanation: Ans is 'c' i.e. 5-10% "The complement system consists of a large number of proteins that together constitute about 10% of the total circulating serum protein"