3) Scientists who have examined the fossil record have noted that some species have changed very little over long
periods of geologic time. The lack of change in such organisms is most likely because
A) the environment that they lived in remained the same, and they were well-adapted to it
B) all members of their population were genetically identical, and they lived in a rapidly changing
environment
C) there was a large amount of variation in their population, and the environment changed frequently
D) they could move between different environments when food supplies became scarce

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.