Which statement best contrasts animals with other living things? a. animals have muscle tissue, whereas other living things do not. b. animals have multiple cells, whereas other living things are single-celled. c. animals have a nucleus within their cells, whereas other living things do not. d. animals have several types of tissue, whereas other living things only have one type.

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.