Assterion : Each enzyme has a substrate binding site in its molecule which forms highly reactive enzyme-substrate complex.
Reason : The enzyme-substrate complex is long-lived and dissociates into its product and unchanged enzyme.

Answer

C

Explanation

A particular substrate molecule is acted upon by a particular enzyme . After coming with the active site (a pocket into which the substrate fits) of the enzyme, the substrate molecules or reactants form a complex called enzyme-substrate complex. The enzyme substrate complex is short lived. In the complexed state, the molecules of the substrate undergo chemical change. The products remain attached to the enzyme for some time so that an enzyme-product complex is also formed. However, the products are soon released and the freed enzyme is able to bind more substrate molecules.