Final answer:
Naïve B cells express CD20 and have immunoglobulin light chains on their surface but not in the cytoplasm.
Step-by-step explanation:
The cell type that expresses CD20 and contains immunoglobulin light chains on the surface but not in the cytoplasm is the naïve B cell. Naïve B cells are a type of lymphocyte that belong to the adaptive immune response system. They are responsible for producing antibodies and have distinct surface receptors, including CD20, which is a marker for B cells.