Question

what kind of inhibitor occupies the active site of the enzyme and prevents it from ever getting to the target substrate? retroactive allosteric non - competitive competitive

Explanation:

Competitive inhibitors bind to the active - site of an enzyme, competing with the substrate for binding, thus preventing the substrate from accessing the active - site. Retroactive is not a type of enzyme inhibitor in this context. Allosteric inhibitors bind to a site other than the active - site. Non - competitive inhibitors also bind to a site other than the active - site and change the enzyme's shape.

Answer:

competitive