What would be required to enable sending emails from their new domain without impacting deliverability?

Northern Trail Outfitters (NTO) uses the SAP domain comms.nto.com and has just opened an office in Australia. They have created a business unit for their new office and want to use the domain comms.nto.com.au to send emails to their Australian customers.

What would be required to enable sending emails from their new domain without impacting deliverability?
A . An additional IP address
B . An additional Sender Authentication Package
C . An additional private domain
D . Register the new domain in Setup > From Address Management

Answer: A