a specific time during development at which a particular event has its greatest consequences and the presence of certain kinds of enviromental stimuli is necessary for development to proceed normally is called

critical period

Explanation:

Critical period: In developmental biology & psychology, the term critical period is defined as the phenomenon that involves an individual's maturational stage in his or her life span in which the nervous system of the person is considered as very sensitive to a few specific environmental stimuli.

If an individual, doesn't receive required stimuli from the environment which is considered as necessary to develop specific functions then it would be difficult for the person to develop those functions later in life.

The critical period was first introduced by John Fiske during 1888.

In the question above, the given statement represents the critical period.