For complement system are correct following hypotheses:

a) are a group of serum proteins, which are involved in the reactions of the nonspecific protection;

b) complement proteins are globulins or glycoproteins;

c) the complement proteins are produced by macrophages, leukocytes, hepatocytes and  contain 5-10% of all blood proteins;

d) the complement system is represented by 20–26 serum proteins that circulate in and out of individual fractions.