Universal Container’s Salesforce Admin set the organization wide default for the contact object to public, read, and write. How would the role hierarchy assist in extending access to records?

Answer options:

A.Role hierarchy will restrict access to the records
B.Role hierarchy will be redundant since the organization wide default is public read and write
C.Role hierarchy will open more access to the records
D.Role hierarchy will not allow managers to access the records

Correct Answer: B 
Role hierarchy will be redundant since the organization wide default is public read and write. Role hierarchy works to extend access to records to the manager, for example. It cannot be used to provide more permission than the profile permission. 
Option A is incorrect because role hierarchy will extend access to the records, not restrict them. But in this scenario, the organization wide default is open, so the role hierarchy is redundant. 
Option C is incorrect. Because the organization wide default is open, the role hierarchy is redundant. 
Option D is incorrect. Because the organization wide default is open so the managers can access the records and at the same time role hierarchy extends access to records such as managers. 
References:

https://help.salesforce.com/articleView?id=admin_roles.htm&type=5

Correct Answer: B 
Role hierarchy will be redundant since the organization wide default is public read and write. Role hierarchy works to extend access to records to the manager, for example. It cannot be used to provide more permission than the profile permission. 
Option A is incorrect because role hierarchy will extend access to the records, not restrict them. But in this scenario, the organization wide default is open, so the role hierarchy is redundant. 
Option C is incorrect. Because the organization wide default is open, the role hierarchy is redundant. 
Option D is incorrect. Because the organization wide default is open so the managers can access the records and at the same time role hierarchy extends access to records such as managers. 
References:

https://help.salesforce.com/articleView?id=admin_sharing.htm&type=5