Which of the following best describes the level of analysis that looks at trait expression across entire populations?

• A. Cellular
• B. Population
• C. Molecular
• D. Organism

Answer: (B)

The correct choice focuses on "population" as the level of analysis concerned with trait expression across entire groups of individuals rather than examining traits at a cellular, molecular, or individual organismal level. In population genetics, researchers study frequencies of alleles and traits within populations, enabling an understanding of how these traits are distributed in larger groups over time and how they may change due to factors like natural selection, genetic drift, and gene flow.

Analyzing traits at the population level allows for insights into patterns of inheritance, genetic variation, and the effects of environmental interactions on those traits, which cannot be deduced solely from observations made at the cellular or molecular levels. This perspective is crucial for understanding evolutionary processes and population dynamics, making it a vital area within the broader field of genetics.