Answer:
C. At least five mass-extinction events have occurred during the last 500 million years.
Explanation:
- The history of mass extinct is related to the five mass extinctions that are caused over by the 350 million years n which many species have disappeared in there short geologic time.
- A massive extinction is caused in the Permian Triassic extinction event i.e about 250 mn years ago which on an estimate has killed 90% of the species.
- The Cretaceous–Paleogene extinction event that occurred over 66 million years ago is known to have wiped out the dinosaurs and many other species.
Answer: ozone concentration
Explanation: The Dobson Unit is the most common unit for measuring ozone concentration. Becuse ozone concentration is hard to measure they use The Dobson Unit.
The correct option is C.
Science is a dynamic subject and it changes all the time. In the science field, research is always on going and when new evidence are discovered about a particular topic, the new evidence are usually used to update the scientific information that is already on ground. All the areas of science listed about have enjoyed scientific updates in the recent past.
hopefully this helps, these are the answers on edge
