Final answer:
An adaptation is a genetically based trait evolved to aid an organism's survival and reproduction by increasing its fitness within its environment. These adaptations result from natural selection and are exemplified in traits like the cheetah's speed or the snow leopard's fur. The correct option is 3) A trait or suite of traits which increases one's fitness.
Step-by-step explanation:
An adaptation is a heritable trait or a set of traits that enhance the survival and reproduction of organisms in their natural environment. Through the process of natural selection, traits that provide a survival or reproductive advantage become more common within a population. This can be seen in the varied beak shapes of finches adapted to different food sources or the thick fur of a snow leopard that facilitates survival in cold climates.
Evolution explains how organisms change over time, with natural selection driving the increase of advantageous traits within a population. As such, adaptations are the result of evolutionary processes that finely tune organisms to their environments. Physiological and genetic adaptations are critical for the success of species in various ecological niches.
An example of evolutionary adaptation is the cheetah's speed, which emerged to improve hunting efficiency. This demonstrates how an adaptation, while genetically based, provides a functional advantage in a specific environmental context. Accordingly, among the options provided, the best definition of an adaptation would be: 3) A trait or suite of traits which increases one's fitness.