Identify the statement that is true about mass extinctions. A. Mass-extinction events are times in the Earth's history when few species evolve. B. The mass extinction of over two-thirds of the species on the Earth was the result of large volcanic eruptions in Hawaii. C. The mass extinction of dinosaurs occurred at the Permian-Triassic boundary. 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.

A. Mass-extinction events are times in the Earth's history when few species evolve.

Explanation:

The extinction that occurred 65 million years ago wiped out some 50 percent of plants and animals. The event is so striking that it signals a major turning point in Earth's history, marking the end of the geologic period known as the Cretaceous and the beginning of the Tertiary period.

A wide range of animals and plants suddenly died out, from tiny marine organisms to large dinosaurs.

Species go extinct all the time. Scientists estimate that at least 99.9 percent of all species of plants and animals that ever lived are now extinct.

i think its c if i'm wrong

force is based upon mass and acceleration.the statement is not always true.

it can be explained from newton's second law of motion.

as per newton's second law of motion the rate of change of momentum is directly proportional to the applied force and takes place along the direction of force.

mathematically it can be written as -

                                              ⇒      

here   k is the proportionality constant whose value is 1.

                                                            [a is the acceleration=dv/dt]

hence we see that force not only depends on mass and acceleration but also on velocity and rate of change of mass. force f will depend on mass and acceleration only when mass is constant.

hence the statement that force is based upon mass and acceleration is false.