Which of the Following Statements About Carbon Dioxide Levels in Earth's

question 45

Multiple Choice

Which of the following statements about carbon dioxide levels in Earth's atmosphere is true?

• A) They peaked around 1950 and have been slowly decreasing since then.
• B) They are high now but are not higher than the highest estimated levels during the last 420,000 years.
• C) They are estimated to be higher now than at any time in the past 420,000 years.
• D) They began to decrease when the use of CFCs stopped.

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Definitions:

Glycoprotein

A protein with covalently attached carbohydrates

Golgi Stacks

A structure within the cell composed of a series of flattened membrane sacs involved in the modification, sorting, and packaging of proteins.

Surface Area

The total area of the external surface of a three-dimensional object.

Spherical Shape

Pertains to objects or entities having the shape of a sphere, which is perfectly round in three dimensions.