A school has a hurdle track that is of a mile long. They are considering extending the track to be of a mile long.The committee wants to know the unit rate of length in the longer track per mile of length in the shorter track to make sure they have enough hurdles for the longer track. What is the unit rate?
A. 1 1/5 miles per mile
B. 1/4 of a mile per mile
C. 1 1/4 miles per mile
D. 1/5 of a mile per mile