Your company has a main office and two branch offices.
The relevant portion of the network is configured as shown in the exhibit.

Each office is configured as a separate routing group. A single SMTP connector connects all three routing groups.

One SMTP virtual server in each office is configured as a bridgehead server for the SMTP connector.
Users report that large e-mail messages sent between the branch offices take more than 30 minutes to be delivered.

You need to ensure that large e-mail messages sent between the branch offices are delivered as quickly as possible.

What should you do?

A.
Configure an additional bridgehead server from the main office for the SMTP connector.

B.
Configure a routing group connector between the main office and the branch offices and an X.400 connector between the branch offices.

C.
Configure a SMTP connector between the branch offices.

D.
Configure the network routers to route all SMTP traffic sent between the branch offices, through the main office.

Explanation:
in this case is the correct answer B, answer D is correct only if you have an intelligent router. With a normal router you can block the smtp traffic only.