What is the first step the Salesforce Admin must complete to set up the partner users?

What is the first step the Salesforce Admin must complete to set up the partner users?

Universal Containers has a community for their partners. They would like to add a new partner company and grant their users access to the Community.
A . Create a partner profile for the company.
B . Add partner contacts to the Community as members.
C . Create the account and enable it as a partner account.
D . Allow partner users to self -register and gain access.

Answer: A