The correct answer is option A) "the environment that they lived in remained the same, and they were well-adapted to it".
Explanation:
One of the basis of evolution is that species that face new environmental conditions tend to develop new traits to survive. The opposite applies to species that have lived in constant environmental conditions, these species are usually well-adapted and have changed very little over long periods of geologic time. Some species of tortoises are examples of animals that had changed very little in their evolutionary history. The hard shells of tortoises is an ancient adaptation that help them to survive in constant environmental conditions.
