In Studies of Dogs Running on Treadmills,results Stemming from a Gradual

Multiple Choice

In studies of dogs running on treadmills,results stemming from a gradual increase in the slope of the treadmills supported the hypothesis that the partial pressure of CO₂ is the feedback signal controlling respiratory rate.However,a related experiment that did not support that hypothesis

A) compared respiratory rates of dogs versus cats.
B) compared sleeping versus barking dogs.
C) changed the speed at which the dogs ran instead of the slope of the treadmills.
D) changed the dogs' motivation by keeping them food-stressed.
E) involved the injection of dissolved O₂ into the dogs' arteries.