The famous K-T extinction occurred about 65 million years ago, at the boundary of the Cretaceous and Tertiary periods, with profound effects on many different taxa, including the dinosaurs. Which is the widely accepted as the cause of this extinction?
A. An impact with an extraterrestrial body, such as an asteroid, as evidenced by the layer of clay demarcating the Cretaceous-Tertiary boundary which contains iridium.
B. A giant supernova had exploded near Earth and the radiation produced and the climate changes.
C. This mass extinction occurred gradually over the course of millions of years, likely as a result of gradual changes in temperature, humidity, sea level, and other environmental properties.
D. None of the above.