**Core Concept**
The differentiation and maturation of B lymphocytes (B cells) involve the expression of specific surface antigens and markers that play a crucial role in their identification and function. B cells are a type of lymphocyte that plays a key role in the adaptive immune response, and their surface markers are essential for their recognition and targeting.

**Why the Correct Answer is Right**
The correct marker for B lymphocytes is CD19. CD19 is a transmembrane glycoprotein expressed on the surface of B cells from the early pro-B cell stage to the mature B cell stage. It is a key component of the B cell receptor complex and plays a crucial role in B cell activation, proliferation, and differentiation. CD19 interacts with CD21 and CD81 to form a complex that facilitates B cell activation through the engagement of the B cell receptor.

**Why Each Wrong Option is Incorrect**
* **Option A:** This is incorrect because CD20 is another surface marker expressed on B cells, but it is not the primary marker for B lymphocytes. CD20 is expressed on mature B cells, but it is not as widely expressed as CD19.
* **Option B:** This is incorrect because CD22 is a surface marker expressed on mature B cells, but it is not the primary marker for B lymphocytes. CD22 is involved in the regulation of B cell activation and differentiation.
* **Option C:** This is incorrect because CD23 is a surface marker expressed on mature B cells, but it is not the primary marker for B lymphocytes. CD23 is involved in the regulation of IgE production and eosinophil activation.

**Clinical Pearl / High-Yield Fact**
CD19 is a crucial marker for B cell malignancies, such as B cell acute lymphoblastic leukemia (B-ALL) and chronic lymphocytic leukemia (CLL). The expression of CD19 on B cells makes it an attractive target for immunotherapies, such as CAR-T cell therapy.

**Correct Answer:** D. CD19.