In this selection, which detail confirms scientist Clay Tabors's description of the global cooldown as "truly
dramatic"?

A. Six years after the impact, sunshine returned to levels
typical of conditions before the impact.

B. The last decade of work has only made it harder to
distinguish between the two potential causes.

C. The sediment contained iridium and glassy debris that
formed from rock vaporized by the impact

D. A high-end estimate of soot totals some 70 billion metric
tons (about 77 billion U. S. short tons)

ASAP 20 points