The increase in atmospheric oxygen during the Proterozoic was caused by ____

a. a decrease in worldwide volcanism.
b. a decrease in the size of oceans.


c. photosynthesis by cyanobacteria.
d. the appearance of land plants.
e. formation of banded iron formations


c

Environmental & Atmospheric Sciences

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A. teratogens B. mutagens C. carcinogens D. neurotoxins

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State-directed capitalism is a system where the government does not own much outright, but it plans and regulates the economy

Indicate whether the statement is true or false.

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What process gives trenches their unique arc-shaped depressions?

a. Spreading b. Volcanic eruptions c. Subduction d. Turbidity e. Erosion

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Who is responsible for the consumption of approximately a quarter of the global oil supply?

A) China B) United States C) India D) United Kingdom

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