D, combination of all the them
Answer: How to protect the environment
It's being estimated that dinosaurs lived on Earth from about 237 million years ago to about 66 million years ago. So answers B and D are definately too "old", while answer A is too "young". I'd pick answer C as it's most probable.
The statement that is not true is: A healthy ecosystem can support an unlimited number of life forms.
Any ecosystem has its limits. No matter is a healthy, in perfect shape, and very large ecosystem, there's always a limit as to how much life forms can the ecosystem support. If the number of life forms surpasses the ability of the ecosystem to support them, than the ecosystem will crash, be destroyed, and experience a lot of changes, with the death of lot of life forms involved in the process as well.
There isn't such thing as an ecosystem that has the ability to support an infinite number of life forms, there's only ecosystems that are able to support limited number of life forms.
A. Spin because in a twirling motion tend to become a spinning type of motion. I think
