Which factors are responsible for high and low tides? O A. Cold and warm ocean currents
OB. The moon's gravity and Earth's rotation
O C. The ocean's conveyor belt and refraction
O D. Earthquakes and volcanoes

Environmental differences within ecosystems are generally caused by

Variety of living organisms; includes genetic, species, and ecological types.

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.