Context: The passage below describes an experiment. Read the passage and then follow the instructions below.

Robert put one two-inch steel nail into each of six test tubes. He added water to three of the test tubes and vinegar to the other three. In each test tube, he completely covered the nail with the same volume of liquid. Robert checked the nails for rust at the same time every day. He recorded how many days it took each nail to become completely covered in rust. Then, he compared the number of days it took nails to rust in water to the number of days it took nails to rust in vinegar.
Figure: a new steel nail on a pile of rusty nails.
Identify the question that Robert's experiment can best answer.
A. Do steel nails take fewer days to rust in water compared to vinegar?
B. Do steel nails rust in fewer days when submerged in a large volume of liquid compared to a small volume?
Determine the correct option from the provided choices and reply with its corresponding letter.
Answer: A