Questions: Question 7 1 pts Which of the following is evidence that the K-Pg Mass Extinction was caused by a bolide? Chicxulub Crater Decreased sea levels Iridium found in layers of rock formed at the same time as the K-Pg boundary Stishovite found around the world

The answer is the third one: Iridium found in layers of rock formed at the same time as the K-Pg boundary.

Explanation for each option:

1. Chicxulub Crater: While the Chicxulub Crater is indeed associated with the bolide impact that is believed to have caused the K-Pg Mass Extinction, the presence of the crater itself is not direct evidence of the extinction event. It is more of a supporting piece of evidence that an impact occurred.

2. Decreased sea levels: This is not evidence of a bolide impact. Decreased sea levels could be caused by various geological processes and are not directly linked to the impact event.

3. Iridium found in layers of rock formed at the same time as the K-Pg boundary: This is the correct answer. Iridium is rare on Earth's crust but is more common in asteroids and comets. The presence of a global iridium layer at the K-Pg boundary is strong evidence of a bolide impact.

4. Stishovite found around the world: Stishovite is a high-pressure form of quartz that can form during impact events. While its presence can indicate an impact, it is not as definitive as the iridium layer in linking the event to the K-Pg Mass Extinction.

In summary, the presence of iridium in rock layers from the K-Pg boundary is the most direct evidence linking a bolide impact to the mass extinction event.