单项选择题

A. R1 will always choose the route through R22.
B. As long as R1's best internal OSPF cost to reach R22 is less than 10.
C. As long as R1's best internal OSPF cost to reach R22 is less than 20.
D. R1 will never choo se the route through R22 if the E1 route through R2 is available.