Oxygen Makes Up Almost 21 Percent of Our Present Atmosphere

Multiple Choice

Oxygen makes up almost 21 percent of our present atmosphere. It is essential to modern life for two reasons. First, oxygen is what we must inhale so that our bodies can 'burn' (oxidize) food, releasing energy to our cells. Second, we depend on oxygen for protection from the ultraviolet radiation from the sun that constantly bombards our planet. Harold V. Thurman, Essentials of Oceanography, 5th. ed.

A) Argument; conclusion: Oxygen is essential to modern life.
B) Argument; conclusion: Oxygen makes up almost 21 percent ... atmosphere.
C) Argument; conclusion: We depend on oxygen ... bombards our planet.
D) Argument; conclusion: Oxygen is what we must inhale ... energy to our cells.
E) Nonargument.