Key and lock hypothesis of enzyme action was given by
A. Fischer
B. Koshland
C. Buchner
D. Kuhne

Hint: The specific action of an enzyme with a single substrate can be stated using a Lock and Key pattern first postulated in 1894. In this the lock is the enzyme and the key is the substrate. Only the correctly sized key that is substrate fits into the key hole that is the active site of the lock that is enzyme.

Complete answer:
> Option A- Fischer: He gave the key and lock hypothesis in 1894, according
to his hypothesis both enzymes and substrate molecules have specific geometrical shape and
This specific shape helps to combine enzymes and the substrate.
The active site of enzymes is rigid in its shape and thus there is no change in the active site
before and after the reaction. It is similar to the system of lock and key pattern.
> Option B- Koshland: Daniel Koshland gave a induced fit model in 1958 that shows when the
active site on the enzymes makes contact with the proper substrate then the enzyme molds
itself to the shape of the molecule.
> Option C- Buchner: Eduard Buchner was born on 20 May 1860 he was a German chemist who
was awarded the 1907 Nobel Prize in Chemistry for his work on fermentation.
> Option D- Kuhne: Wilhelm Friedrich Kühne was a German physiologist and he is best known
today for coining the word enzyme.

So the correct answer is Option A- Fischer.

Note: Enzyme activity is regulated by several factors that affect the rate at which enzymatic
reactions takes place- these are temperature, pH, enzyme concentration, substrate
concentration, and the presence of any inhibitors or activators are the main factors.