What is an administrative support specialist?

The answer here is: A and B.

A because according to: https://help.salesforce.com/articleView?id=territories_def.htm&type=0 -

Quote: A territory is a flexible collection of accounts and users where the users have at least read access to the accounts, regardless of who owns the account........You can also control users’ access to the opportunities and cases associated with the accounts in the territory, regardless of who owns the records. END

Allow multiple forecasts for each user.
Grant access to related records based on account sharing.

Territory hierarchy is about assigning users to opportunities. Role hierarchy is about broadening visibility to records up the chain of command so managers can see records owned by their subordinates https://resources.docs.salesforce.com/204/15/en-us/sfdc/pdf/salesforce_territories_implementation_guide.pdf