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".
Q: They cut up an avocado and put it on a sandwich. They put mayonnaise on top of the sandwich. they <sep> (A) add grated mayo on top which they layer with dressing. (B) cut on the cutting board and the sandwich is done. (C) cut a piece of bread on a cutting board. (D) put a piece of bread on top of the sandwich.
A:
D