Which statement best summarizes biological evolution by natural selection?

• A. A sudden appearance of complex, perfectly adapted organisms without ancestral forms.
• B. A change in allele frequencies in a population over generations, driven by heritable variation and differential reproductive success.
• C. The process by which individual organisms change their traits during their lifetime in response to need or effort.
• D. The movement of organisms from one habitat to another, resulting in no genetic change across generations.

Answer: (B)

Verified step by step guidance

1. Understand that biological evolution by natural selection refers to changes occurring at the population level, not changes within an individual organism's lifetime.
2. Recognize that evolution involves changes in allele frequencies, which are variations of genes, within a population over multiple generations.
3. Identify that these changes are driven by heritable genetic variation, meaning traits must be passed from parents to offspring.
4. Acknowledge that differential reproductive success means individuals with certain heritable traits are more likely to survive and reproduce, passing those traits on more frequently.
5. Summarize that biological evolution by natural selection is best described as a change in allele frequencies in a population over generations, driven by heritable variation and differential reproductive success.