What Evidence Suggests When Oxygen Gas First Became a Significant

question 20

Multiple Choice

What evidence suggests when oxygen gas first became a significant part of Earth's atmosphere?

• A) multi-celled microorganisms that breathed oxygen
• B) fossils of dinosaurs
• C) molten rock from volcanoes that were rich in oxygen
• D) rusty rocks indicating oxidized iron
• E) the presence of water vapor in the atmosphere

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Definitions:

Reinforced

Strengthened or made more effective through added support, material, or structure.

Eliminated

Refers to the removal or deletion of something, making it no longer present or effective.

Identified

Recognized or discovered to be a certain person or thing.

Extinction

The process by which a species, genus, or family becomes permanently extinct, marking the end of its survival on Earth.