Q: 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 group of women are inside a dark gym. they <sep> (A) are all riding on recumbent bikes. (B) are then shown synchronizing up and down on the bars on one side. (C) all have fencing gear on as they bounce up and down on the mats. (D) are bouncing back and forth on a loose mat.
A:
A