Which of the following statements about coral reef preservation efforts is true? a. in order to preserve coral reefs, all aquarium trade in coral reef organisms must end. b. legislation has had no impact on coral reef preservation efforts. c. various preservation methods have had some positive impact on coral reef preservation. d. education of fishermen has eliminated all coral reef loss.

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.