Why is the sales manager unable to view the contact?

A sales manager cannot view a contact owned by a salesperson. The salesperson is below the sales manager in the role hierarchy.

Why is the sales manager unable to view the contact?
A . Contact sharing settings have Grant Access Using Hierarchies unchecked.
B . The contact is NOT linked to an account.
C . The contact has NOT been manually shared with the manager.
D . Contact sharing settings are Private.

Answer: D