The basic structure of Ig molecule is

A、A tetrapeptide chain structure consisting of two different heavy chains and two different light chains
B、A dipeptide chain structure consisting of one heavy chain and one light chain
C、A tetrapeptide chain structure consisting of two identical heavy chains and two identical light chains
D、A tripeptide chain structure consisting of one heavy chain and two light chains
E、A tetrapeptide structure consisting of four identical peptide chains