Why do we create a virtual router?

Question $3$ options:

a$)$

it allows for a broadcast domain to be separated into logical sub networks

b$)$

it allows the firewall to do routing functions so the firewall and device behind it can access other networks and the Internet

c$)$

it secures our inside network so hackers cannot access our inside network

d$)$

it allows for broadcast messages to be sent to the entire network