Refer to the exhibit.W

Refer to the exhibit.Which is the most efficient summarization that R1 can use to advertise its networks toR2？（）

• A172.1.4.0/22
• B172.1.0.0/21
• C172.1.0.0/22
• D172.1.4.0/25 172.1.4.128/25 172.1.5.0/24 172.1.6.0/24 172.1.7.0/24
• E172.1.4.0/24 172.1.5.0/24 172.1.6.0/24 172.1.7.0/24