Final answer:
Adaptation is best described by a heritable trait that helps an organism survive and reproduce in a specific environment, such as a beetle's mutation for digesting varied foods during food scarcity. This trait, if beneficial, will be favored by natural selection.
Step-by-step explanation:
The statement that best describes adaptation is: C. A beetle hatches in time of food shortage with a mutation that contains enzymes to digest a greater variety of food. An adaptation is a heritable trait that aids the survival and reproduction of an organism in its present environment. This definition is based on the evolutionary principle that characteristics which enhance an organism's ability to survive and reproduce will tend to increase in frequency over time through the process of natural selection. For instance, a mutation that allows a beetle to digest a greater variety of food would be beneficial during a time of food shortage and would likely spread through the population.
As environments change, natural selection causes the characteristics of the individuals in a population to track those changes. This means that traits which were once beneficial may become less so, and vice versa, as the conditions that organisms face evolve. Adaptations are therefore not constant but can shift in response to environmental pressures.