Final answer:
The heavy chain immunoglobulin is the lymphocyte receptor gene that possesses a D gene segment, which is essential for creating a diverse array of antigen-binding sites in B-cell receptors.
Step-by-step explanation:
The lymphocyte receptor gene that possesses a D gene segment is the heavy chain immunoglobulin. This is because the variable region of the B-cell receptor (BCR) heavy chain is composed of variable (V), diversity (D), and joining (J) segments. Genetic rearrangement of these segments allows for a vast diversity of antigen-binding sites. The light chain immunoglobulin does not have a D gene segment; it only consists of V and J segments.