Which Statement About Oxygen and Ancient Earth Is True

question 23

Multiple Choice

Which statement about oxygen and ancient Earth is true?

• A) The atmosphere of early Earth contained almost as much free oxygen as present-day Earth,but most of this oxygen was lost in the Cambrian.
• B) Early bacteria generated free oxygen as a by-product of the chemical splitting of water.
• C) The oxygen-generating cyanobacteria have gone extinct.
• D) Oxygen concentration increased from near zero to near present-day levels in a nearly straight line upwards.
• E) Early bacteria generated free oxygen as a by-product of the chemical splitting of carbohydrates.

---

Definitions:

Great Depression

A severe worldwide economic depression that took place mostly during the 1930s, beginning in the United States.

Racism

Racism is the belief that a visible characteristic of a group, such as skin color, indicates group inferiority and justifies discrimination.

Poverty

A state or condition in which a person or community lacks the financial resources and essentials for a minimum standard of living.

Income Gap

The disparity in the distribution of income within a population, typically between different socio-economic groups.