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 woman is brushing her teeth in a bathroom. someone <sep> (A) is filming her behind her. (B) is standing behind them. (C) rides a bike around the bathroom. (D) is putting toothpaste on her teeth.
Output:
A