What is one negative effect that predators have on a prey population? a. predator populations will stay consistent regardless of the prey population. b. the predator population will stay high in order to maintain a low prey population. c. the predator's behavior will cause the prey to behave differently to increase their population. d. predator populations that increase allow for higher prey populations.

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.