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 man is on a playground with his dogs. The three dogs run with him in circles around the equipment, and up the stairs. they <sep> (A) stretch, then walk through the door. (B) help each other pick up the slack line. (C) slide down the slides behind him happily. (D) stop and see what's going on.
C