In non-competitive inhibition:
1. the substrate and inhibitor cannot bind to the enzyme at the same time
2. the inhibitor binds only to the substrate-enzyme complex
3. the inhibitor can bind to the enzyme at the same time as the enzyme's substrate
4. the binding of the inhibitor to the enzyme reduces its activity but does not affect the binding of substrate
(d) A non-competitive inhibitor does bind to the active site for the substrate and therefore does not affect the binding of the substrate.