Instructions: 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".
Input: A little boy is riding inline skates down a driveway. he <sep> (A) waves his arms, trying to keep his balance. (B) goes around curves too fast to be seen, but then takes a right turn. (C) is swinging front and back and side to side as he skates. (D) knocks over his skateboard.
Output:
A