Which of the following statements is NOT correct concerning the regulation of the purine biosynthetic pathway?

A)PRPP competitively inhibits the enzyme Gln:PRPP amidotransferase.
B)ADP and GDP are feedback inhibitors of ribose-5-phosphate pyrophosphokinase.
C)"A" and "C" nucleotides allosterically inhibit glutamine phosphoribosyl pyrophosphate amidotransferase (Gln:PRPP amidotransferase).
D)The rate of IMP formation is dependent on the levels of the adenine and guanine nucleotides produced.