What best describes the role of molecular oxygen (O2) in aerobic respiration? A. It accepts electrons when reacting to form water.
B. It combines with carbon and hydrogen to form glucose.
C. It is released when glucose breaks apart.
D. It reacts to form carbon dioxide and water.

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.