"No wind had blown for weeks, and each bough was fully freighted. Each time he had pulled a twig he had communicated a slight agitation to the tree -- an imperceptible agitation, so far as he was concerned, but an agitation sufficient to bring about the disaster. High up in the tree one bough capsized its load of snow. This fell on the boughs beneath, capsizing them. This process continued, spreading out and involving the whole tree. It grew like an avalanche, and it descended without warning upon the man and the fire, and the fire was blotted out! Where it had burned was a mantle of fresh and disordered snow."
Which explanation best describes the movement of the tree in the passage?
A. The slight movement is strong enough to cause an avalanche.
B. The slight movement is causing the entire tree to move.
C. The slight movement is difficult to identify.
D. The slight movement is nonexistent.
