Which of the following keep high oxygen and low oxygen blood from mixing in the frog's ventricle? a. the spongy irregular surface inside the heart b. the coordinated contractions of the atria c. a dividing wall to separate the ventricle into two equal halves d. a valve in the conus arteriosus

In an experiment examining the effects tai chi on arthritis pain, callahan (2010) selected a large sample of individuals with doctor-diagnosed arthritis. half of the participants immediately began a tai chi course and the other half (the control group) waited 8 weeks before beginning. at the end of 8 weeks, the individuals who had experienced tai chi had less arthritis pain that those who had not participated in the course.