Identify the statement that is true about mass extinctions. Choose one: A. The mass extinction of dinosaurs occurred at the Permian-Triassic boundary. B. The mass extinction of over two-thirds of the species on the Earth was the result of large volcanic eruptions in Hawaii. C. Mass-extinction events are times in the Earth's history when few species evolve. D. A mass extinction may happen when a comet or asteroid impact starts a chain of events that blocks sunlight for weeks or even years.

D. A mass extinction may happen when a comet or asteroid impact starts a chain of events that blocks sunlight for weeks or even years.

Explanation:

Mass extinction: An event in the history of the Earth when a large portion of the living species become extinct. Mass extinction has happened a lot of times and every time life finds a way to come back, evolve and adapt to the new conditions.

The proofs of closest extinction can be found in the extinction of dinosaurs. Widely accepted reason behind this extinction is thought to be strike of a comet or an asteroid around 65 million years back. Because of this impact a chain of event started. A lot of dust and gases was filled in the atmosphere which blocked the sunlight to reach Earth for around 2-3 years.