Final answer:
The short-term response of individuals to changes in an environment, such as shivering in cold, is reversible and not genetic. Adaptations, on the other hand, are genetic changes within a population that result from evolutionary processes and are irreversible. The correct answer to the student's question is b) Short-term response is reversible; adaptations are irreversible.
Step-by-step explanation:
The difference between the short-term response of individuals to changes in an environment and the adaptations observed in populations due to environmental changes is significant. A short-term response is often physiological or behavioral and reversible. For example, if a human enters a colder climate, they may shiver and experience goosebumps as a short-term response. This reaction does not involve any genetic changes and can be reversed when the individual returns to a warmer environment.
On the other hand, adaptations occur at the population level and result from the process of evolution by natural selection. These reflect genetic changes that accrue over generations, highlighting a better fit of the population to the changed environment. As such, adaptations are typically irreversible; once they occur, they become part of the population's gene pool. An example of adaptation is the varying beak sizes of the finches in the Galápagos Islands, which evolved over generations to better exploit the available food resources.
Therefore, the correct answer to the student's question is option b) 'Short-term response is reversible; adaptations are irreversible'. Short-term responses do not result from genetic changes and are not a product of the evolutionary process, hence they are not adaptations.