A concept that there is a specific time in an organism's development during which external factors have a unique and irreversible impact is:

A. ethology
B. equifinality
C. critical period
D. zone of proximal development

critical period

Explanation:

During the lifespan of an organism, there is a developmental stage during which the environmental stimuli have the greatest impact on the nervous system and hence, the external factors have an irreversible impact on the organism's development. This is termed as the critical period.During the critical period a person develops several essential life skills such as vision, first language, hearing, etc. and a failure to receive the external factors during this critical period, may make it nearly impossible to learn those life skills at a later stage. The critical period usually begins during the prenatal stage and continues until adolescence whereas closes at around adulthood. During the critical period, the cellular events, as well as sensory experiences, need to coincide to function successfully and generate an impact.