Antibody molecule has:

The correct option is Two peptide chain.

An antibody molecule (immunoglobulin) is a Y-shaped glycoprotein that plays a vital role in the body's immune response. The classification and arrangement of its peptide chains are explained below:
1. Two Distinct Types of Chains: The structure of an antibody is characterized by two structurally distinct types of polypeptide chains: the heavy (H) chains, which have a larger molecular weight, and the light (L) chains, which have a smaller molecular weight.
2. Two Symmetrical Halves: The functional antibody monomer is composed of two identical halves. Each half consists of one heavy chain and one light chain bound together by disulfide linkages. Thus, the molecule is formed by the dimerization of these two identical peptide-chain units.