In this task, you are given a context and four options. Each option is a suggested ending for the context. You should read the context and pick the best ending for the context. Please answer with "A", "B", "C", and "D".

They are swaying their hands above their heads from left to right. Then the instructor demonstrates arm strength by tapping his right arm over his extended left arm. both the instructors <sep> (A) demonstrate arm movements attempting to instil a physical strength into their body. (B) stand facing each other as they demonstrate slow and gradual hand movements. (C) take turns demonstrating arm strength movements at the same time. (D) defecate profusely while trying to get up.
B