Which phrase best defines evolution in a biological population over time?

• A. A change in allele frequencies in a population across generations
• B. The origin of life from nonliving matter
• C. An individual organism changing its traits during its lifetime to better fit the environment
• D. A sudden, goal-directed increase in complexity in all organisms

Answer: (A)

Verified step by step guidance

1. Understand that evolution in biology refers to changes that occur at the population level, not changes within an individual organism's lifetime.
2. Recall that alleles are different versions of a gene, and the frequency of these alleles in a population can change over generations.
3. Recognize that evolution is defined as the change in allele frequencies in a population over time, which can result from mechanisms like natural selection, genetic drift, mutation, and gene flow.
4. Eliminate options that describe individual changes (like an organism changing traits during its lifetime) or non-biological processes (like the origin of life from nonliving matter).
5. Conclude that the best definition of evolution in a biological population over time is 'a change in allele frequencies in a population across generations.'