Antibodies are proteins, also called polypeptides, used by the immune system to identify and neutralize pathogens such as viruses and bacteria.
Each antibody es different and recognizes a specific antigen.
Antibodies are large proteins with a Y shape, with two large heavy chains (blue and yellow) and two shorter lighter chains (green and pink). The antigen bonds to the tips of the "Y", between the light and the heavy chain.
This means the right option is D, antibodies are composed of Two light and two heavy polypeptide chains.