Which route address is the best summary of these network addresses?

You design a network with the following network addresses:

192.168.168.0

192.168.169.0

192.168.170.0

192.168.171.0

192.168.172.0

192.168.173.0

192.168.174.0

192.168.175.0

Which route address is the best summary of these network addresses?

A.
192.168.0.0/16

B.
192.168.168.0/21

C.
192.168.0.0/24

D.
192.168.171.128/3

E.
192.168.175.0/3

F.
None of the above

Explanation:

Route Summarization is called route aggregation. Route aggregation creates one route in the routing table represents many other routes. Summarizing routes reduces the routing update traffic and reduces the number of routes in the routing table and overall router overhead in the router receiving the routes
Example of creating Summary Route:

192.168.168.0 = 11000000 10101000 10101 000 00000000 192.168.169.0 = 11000000 10101000 10101 001 00000000 192.168.170.0 = 11000000 10101000 10101 010 00000000 192.168.171.0 = 11000000 10101000 10101 011 00000000

192.168.172.0 =11000000 10101000 10101 100 00000000
192.168.173.0 = 11000000 10101000 10101 101 00000000 192.168.174.0 =11000000 10101000 10101 110 00000000
192.168.175.0 =11000000 10101000 10101 111 00000000

Number of Common Bits = 21
Number of Non-Common Network Bits = 3
Number of Host Bits = 8

So Answer 192.168.168.0/21 is correct.