What mass extinction was responsible for the extinction of the dinosaurs?

Some believe it was a natural occurring ice age.

Others say it resulted from the impact of an asteroid, comet, or meteor that released enough debris into the atmosphere to trigger a "impact winter" that blocked sunlight from reaching the ground and prevented plants needing photosynthesis from growing resulting in the starvation of dinosaurs and other creatures.

It could also have been the great flood that has been recorded all over the world and the dinosaurs never made it into Noahs ark :)