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

Cara applied a thin layer of wax to the underside of her snowboard and rode the board straight down a hill. Then, she removed the wax and rode the snowboard straight down the hill again. She repeated the rides four more times, alternating whether she rode with a thin layer of wax on the board or not. Her friend Preston timed each ride. Cara and Preston calculated the average time it took to slide straight down the hill on the snowboard with wax compared to the average time on the snowboard without wax.
Figure: snowboarding down a hill.
Identify the question that Cara and Preston's experiment can best answer.
A. Does Cara's snowboard slide down a hill in less time when it has a layer of wax or when it does not have a layer of wax?
B. Does Cara's snowboard slide down a hill in less time when it has a thin layer of wax or a thick layer of wax?
Pick the correct answer from the listed options and provide the letter of the selected option.

A