In Comparing the Antigen-Binding Site of an Antibody to the Binding

In comparing the antigen-binding site of an antibody to the binding site of an enzyme, which statement is true?

A) Both change the covalent structure of the substance they bind.
B) Both leave the structure they bind unchanged.
C) An antibody changes the covalent structure of its bound antigen, and an enzyme does not change the covalent structure of its bound substrate.
D) An antigen changes the covalent structure of the antibody to which it binds, and a substrate does not change the covalent structure of the enzyme to which it binds.
E) An antibody does not change the covalent structure of its bound antigen, and an enzyme does change the covalent structure of its bound substrate.