Biologists look at how organisms are related and when they first appeared on Earth. Which of the following is true about the organisms that live on Earth today? A. All organisms that have ever lived on Earth can still be found alive today.

B. Some of the organisms alive today have been around for 4.6 billion years.

C. The organisms alive today are the same as the ones found in fossils.

D. The organisms alive today evolved from organisms that previously lived on Earth.