Which of the following best describes an example of how an enzyme inhibitor can work in a reaction catalyzed by an enzyme?

The enzyme inhibitor catalyzes the reverse reaction, which counteracts the work of the enzyme.
The enzyme inhibitor attacks and destroys the enzyme, which prevents the enzyme from helping in the reaction.
The enzyme inhibitor binds to the products of the reaction, which makes the work of the enzyme unproductive.
The enzyme inhibitor fits into the enzyme's active site, which prevents the enzyme from catalyzing the reaction.

The most appropriate answer would be The enzyme inhibitor fits into the enzyme's active site, which prevents the enzyme from catalyzing the reaction.

Enzyme inhibitors are the chemical substances which inhibit the functions of the enzymes by binding to the enzyme.

They are broadly of two types:

Irreversible inhibitors: They bound to the enzyme with the help of covalent bond and reduces the affinity of enzyme towards substrate by changing the shape of the active sites.

Reversible inhibitors: Theses are the molecules which attach to the enzymes with the help of non-covalent bonds such as hydrogen bonds, ionic bond, hydrophobic interactions et cetera.

They can be of various sub-types:

Competitive inhibitors: They compete with substrate for binding to the active site.
Uncompetitive inhibitors: They binds enzyme-substrate complex and can be overcome by increasing the substrate concentration.
Non-competitive inhibitors: They bind to site (allosteric site) other than active site.