Answer: B)heavy-chain constant segments
Step-by-step explanation:
The immunoglobulin are the antibodies that are found in the serum. There are five classes of these antibodies in the serum. These includes the IgG, IgD, IgA, IgM and IgE. They are classified on the basis of difference in the type of heavy chain. IgG, IgA, IgE, IgD contains μ, α, ε-, and δ- heavy chains respectively.
This variation helps each immunoglobulin class to generate a different kind of immune response during different stages of body defense.