Refer to the exhibit.

What is the most efficient summarization that R1 can use to advertise its networks to R2?

A.
172.1.4.0/25
172.1.4.128/25
172.1.5.0/24
172.1.6.0/24
172.1.7.0/24

B.
172.1.0.0/22

C.
172.1.4.0/24
172.1.5.0/24
172.1.6.0/24
172.1.7.0/24

D.
172.1.0.0/21

E.
172.1.4.0/22

Explanation:
When the subnet mask is /22, R1 can advertise its networks to R2.