Context: Kelly is sledding with her friends. She notices that some of them go faster down the sledding hill. She wonders what factors affect sledding speed. So, she decides to design an experiment. She has the following supplies available:
access to a small snow-covered hill at the park
a small plastic sled
a large plastic sled
a rubber inner tube sled
a stopwatch
Using only these supplies, which question can Kelly investigate with an experiment?
A. Does a plastic sled or a wooden sled go down a hill faster?
B. Does a rubber inner tube sled go faster down a small hill or down a big hill?
C. Does a rubber inner tube sled or a plastic sled go faster down a hill?
Select the correct answer from the provided options and reply with the letter associated with it.

C