What Is Still Lacking in the Hypothesis of an Asteroid

What is still lacking in the hypothesis of an asteroid impact as the cause of the end-Cretaceous mass extinction?

A) evidence of the location where an asteroid hit Earth
B) evidence that an asteroid hit Earth at the time of the extinctions (65 million years ago)
C) a convincing explanation of why mammals radiated after the event
D) a convincing explanation of why some lineages survived while others vanished