- A The physically strongest individuals in a population are generally most able to survive long enough to reproduce according to conventional understanding
- B Organisms best adapted to their environment have highest reproductive success ('fittest' = most reproductively successful, not necessarily strongest)
- C The fastest-moving animals in a population tend to most consistently escape predation and ultimately survive in routine practice overall in most cases
- D All organisms within a population tend to survive and reproduce at roughly similar, fairly unvarying rates under typical conditions according to standard textbooks
Correct answer: B. Organisms best adapted to their environment have highest reproductive success ('fittest' = most reproductively successful, not necessarily strongest)
Explanation: 'Fitness' in evolutionary biology means reproductive success, not physical strength. An organism is 'fit' if it successfully produces surviving offspring in its environment. A slow organism with many offspring is more fit than a fast organism with fewer. Herbert Spencer coined the phrase; Darwin used it to explain natural selection.
Concept context
Origin of life, Darwin's theory, natural selection, speciation, and evidence for evolution.