Every few years, sailboats of different countries compete in a race for a trophy called the America's Cup. The boats sail over the same distance. What, besides the distance, is needed to find out the speed of each boat in the race?
A.
the size of each boat in the race
B.
the speed of the wind during the race
C.
the skill of the crew of each boat in the race
D.
the time it takes each boat to finish the race