There is ____"u" and ___"h" in the word"house".[ ]

A. an, a

B. an, an

C. a, an

Two dogsled teams raced across a 300-mile course in Wyoming. Team A finished the course in 3 fewer hours than did team B. If team A’s average speed was 5 miles per hour greater than that of team B, what was team B’s average speed, in miles per hour ？（）

A. 12

B. 15

C. 18

D. 20

E. 25