All of the following are postulates of the clonal selection theory EXCEPT:

• A. Each B lymphocyte bears a single type of receptor with a unique specificity.
• B. BCR occupation is required for cell activation.
• C. Differentiated cells derived from an activated B lymphocyte bear receptors of similar specificity as the parent cell.
• D. B lymphocytes bearing receptors for self-molecules are destroyed at an early stage.
• E. All are postulates of the clonal selection theory.