What is the biological definition of a species? a. a group of organisms that look alike b. a group of similar organisms that live in different areas c. a group of similar organisms that live in one particular area d. a group of organisms that can mate with each other and produce fertile offspring

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.