Answer
b.
Work Step by Step
An adaptive trait is one that not only increases the fitness of an individual, but it can also be passed down to that individual's offspring. Fitness is defined as how well an individual is suited to live in its environment. Over time and many generations, those individuals with adaptive traits will most likely be the ones who survive the longest and produce the most offspring.
Not all traits that arise by mutation are adaptive because they may not be beneficial to the individual; also, if the mutation does not arise in the germ cells, it cannot be passed down to offspring.
