Given the task definition and input, reply with output. 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".

A little boy is climbing up the stairs of a play gym, he stops once and points at a red tube opening but passes it. He gets to the red tube slide at the top and points to it and then slides down. once <sep> (A) he gets to the bottom, he waits, lifts his legs and slides but doesn't slide. (B) on the ground he walks around for a bit then turns around and points up. (C) on, he slides across it and has a great time sliding down. (D) he reaches the bottom, he comes up and grabs the gear that is underneath him and begins to slide back down.
B