Final answer:
Evolution is NOT a chronic response to environmental change like acclimatization or acclimation. Instead, it refers to changes in allele frequencies in a population over time due to natural selection.option 4 is the correct answer.
Step-by-step explanation:
The aspect which is NOT a chronic response (acclimatization or acclimation) to a changing external environment is evolution. Acclimatization and acclimation both refer to the process of an organism adjusting to a new environment over a period of time such as days or seasons.
For instance, when animals migrate to higher altitudes, they undergo acclimatization by increasing the red blood cell count to compensate for the lower oxygen levels.
Moreover, acclimation is an adjustment to environmental change observed under laboratory conditions over days. Unlike these responses, adaptation occurs over longer time-scales involving changes in allele frequencies within a population as a result of natural selection, and it is a feature of evolution. This gradual change is essential to the survival and reproductive potential of organisms, as it allows populations to maintain a "fit" to their environment across generations.