Researchers Are Testing the Hypothesis That High Levels of Carbon

Multiple Choice

Researchers are testing the hypothesis that high levels of carbon dioxide in the blood trigger panic attacks. Half of the participants breathe carbon dioxide-enriched air, and the other half breathe normal air, then measured panic attack symptoms. In this study _______ is the independent variable and _______ is the dependent variable.

A) carbon dioxide-enriched air; regular air
B) regular air; carbon dioxide-enriched air
C) type of air; panic attack symptoms
D) panic attack symptoms; type of air