Answer + Explanation:
D. If common ancestry is true, then evolution (change over time) must have happened.
Common ancestry is a fundamental concept in evolutionary theory because it implies that all living organisms share a common ancestor and have diverged from one another through a process of descent with modification. This means that over time, species change and evolve into new forms, and those new forms share a common lineage with their ancestors.
If common ancestry were not true, then the theory of evolution by natural selection would not make sense, since it relies on the idea that species change over time through a process of descent with modification.
Additionally, common ancestry provides a framework for understanding the diversity of life on Earth and how different species are related to one another. By tracing the evolutionary history of different groups of organisms, scientists can better understand their biology, behavior, and ecology, and can make predictions about how they may respond to environmental changes or other challenges.