Final answer:
Multiple genes should be compared when studying population genetics because traits are often polygenic and a single gene may not provide a comprehensive view of genetic diversity and adaptability within a population.
Step-by-step explanation:
Understanding the genetics of a population requires analyzing multiple genes because traits are often determined by the interaction of several genes rather than a single gene. When assessing population genetics, it's important to consider that many human traits are polygenic, meaning that they are influenced by multiple genes each with their own alleles, such as the eight or more genes that determine eye color in humans. Additionally, a single gene can have multiple effects, and variations within a population are necessary for adaptability and survival. For instance, three alleles (IA, IB, and i) are responsible for the ABO blood type system, showcasing the diversity within even a single genetic trait.
Hence, comparing several genes provides a broader view (option b) into the complex inheritance and interaction patterns within a population. This approach enhances our understanding of genetic diversity, the effects of selective forces on populations, and helps to predict how these will change over time. In contrast, analyzing a single gene could give a skewed or incomplete picture of genetic variation and the potential for adaptation within a population.