What is the simplest way to configure routing between the regional office network 10.89.0.0/20 and the corporate network?

Refer to the exhibit.

What is the simplest way to configure routing between the regional office network 10.89.0.0/20 and the corporate network?
A . router1(config)#ip route 10.89.0.0 255.255.240.0 10.89.16.2
B . router2(config)#ip route 10.89.3.0 255.255.0.0 10.89.16.2
C . router1(config)#ip route 10.89.0.0 255.255.240.0 10.89.16.1
D . router2(config)#ip route 0.0.0.0 0.0.0.0 10.89.16.1

Answer: D

Explanation:

The fourth command makes it possible for all hosts beyond R2 and all hosts beyond R1 to interact with each other, hence it is the most simplest technique.