In an ecosystem, material can be recycled. Which of the following materials can cycle through this ecosystem ?

A. water
B. oxygen
C. Carbon
D. All of these

Idon’t know the answer and i’ve been stuck on it for a while now skskskskks

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.

They live on every continent except antarctica