Answer
B.
Work Step by Step
Evolutionary fitness is measured by contribution of fertile offspring to the next generation, not by size, strength, or any other phenotypic measure itself, like color or volume of sound produced. Thus, A. is wrong, and D. can be eliminated as directly contradicting the definition of evolutionary fitness. C. is incorrect because the contribution of offspring is relative to others in the population, and animals like salamanders and jellyfish or plants like oak trees don't consciously chose the number of their offspring--it's all about natural selection determining this.
