Each antibody has  \(\underline{A}\) polypeptide chains, \(\underline{B}\) small chains called \(\underline{C}\) chains and \(\underline{D}\) longer chains called \(\underline{E}\) chains. The antibody, therefore, is represented as \(\underline{F}\).

Here A to F refers to:

A–four, B–two, C–light, D–two, E–heavy, F–H ₂L₂

The correct answer is Option (1) -A–four, B–two, C–light, D–two, E–heavy, F–H ₂L₂

Antibodies, also known as immunoglobulins, are protein molecules produced by B-cells as part of the immune response. Each antibody consists of several polypeptide chains. The structure of an antibody includes two types of chains: light chains and heavy chains.

In the given options, the correct representation of the antibody structure is as follows:

A – Antibodies have four polypeptide chains in total.

B – There are two small chains called light chains.

C – The small chains are referred to as light chains.

D – Antibodies have two longer chains called heavy chains.

E – The longer chains are referred to as heavy chains.

F – The antibody structure is represented as H₂L₂, indicating two heavy chains and two light chains.

Therefore, the correct option is (a) A–four, B–two, C–light, D–two, E–heavy, F–H₂L₂.