Which of these statements about enzyme inhibitors is true?

• A. A competitive inhibitor binds to the enzyme at a place that is separate from the active site.
• B. A noncompetitive inhibitor does not change the shape of the active site.
• C. When the product of an enzyme or an enzyme sequence acts as its inhibitor, this is known as positive feedback.
• D. Inhibition of enzyme function by compounds that are not substrates is something that only occurs under controlled conditions in the laboratory.
• E. The action of competitive inhibitors may be reversible or irreversible.