Universal Containers has the Account object ' s Organization-Wide Default set to Private.

The correct answer is A. Sharing rules.

Because the Account OWD is Private, users can’t automatically see records owned by users in another branch of the role hierarchy. Salesforce sharing rules are used to extend record access beyond the organization-wide default and role hierarchy. Salesforce documentation states that sharing rules grant additional access to users in public groups, roles, or territories.

Why others are incorrect:

B. Public groups can be used inside a sharing rule, but the public group alone does not share records.

C. Aliases are user display shortcuts, not security controls.

D. Assignment rules assign records; they do not grant cross-team record visibility.

===========