We have to check if the result of each proportion is the same as 9 miles per hour, which is the ratio given after simplifying
A. 27 miles in 4 hours is equal to 6.75 miles per hour, therefore is not correct
B. 54 miles in 6 hours is equal to 9 miles per hour, therefore is correct
C. 36 miles in 5 hours is equal to 7.2 miles per hour, therefore is not correct
D. 9 miles in 1 hour is equal to the given ratio, then this answer is correct.
The correct answers are B and D.