Which one of the following pairs of nitrogenous bases of nucleic acids, is wrongly matched with the category mentioned against it?

• A.  Thymine, Uracil             -   Pyrimidines
• B.  Uracil, Cytosine             -   Pyrimidines
• C.  Guanine, Adenine          -   Purines
• D.  Adenine, Thymine          -   Purines