human
Question: Some localized layers of rock contain the element iridium. Iridium is most often found in space objects such as meteoroids and asteroids. The discovery of these iridium-containing layers has been matched to which phenomena in Earth's history?

Choices:
A) tectonic plate separations
B) mass species extinctions
C) orbital path changes
D) magnetic pole reversals
gpt
The correct answer is 1: mass species extinctions.