You are studying regulation of a prokaryotic operon. Experiments show that expression of the operon is increased when levels of biosynthetic product from that pathway are low. Based on this information, what is a likely mode of regulation?
A. The product binds a repressor, allowing it to bind the operator.
B. The product binds a repressor, preventing it from binding the operator.
C. The product binds an activator, helping RNA polymerase to bind the promoter.
D. The product binds to the biosynthetic enzymes, blocking them directly.
Answer: A
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