Scientists are examining the possible role of a large asteroid in the Cretaceous mass extinction event. A large asteroid strike would likely have caused rapid climate cooling and diffusion of sunlight. Which of the following statements are the best null and alternative hypotheses when scientists look at the geologic evidence of extinction related to the asteroid strike?

A) Null: The rate of extinction would be steady over the entire length of time the climate was altered.
Alternative: The rate of extinction would be greatest immediately before the asteroid strike.
B) Null: The rate of extinction would gradually decrease over the entire length of time the climate was altered.
Alternative: The rate of extinction would be at its lowest immediately after the asteroid strike.
C) Null: The rate of extinction would be steady over the entire length of time the climate was altered.
Alternative: The rate of extinction would be greatest immediately after the asteroid strike.
D) Null: The rate of extinction would gradually decrease over the entire length of time the climate was altered.
Alternative: The rate of extinction would be at its greatest immediately after the asteroid strike.