Universal Container company’s sales VP reported that one the users can view records related to the account although he is not the owner of the record and his profile is a system administrator. Why could this be happening in an organization that has a sharing model which is private? (Choose 2 options)

Answer options:

A.The owner of the account is the user manager within the role hierarchy.
B. Field level security for the fields is accessible.
C.The user has full access to the account object through his profile.
D.The user is added to the account team as a member.

Correct Answer: A and D 
Role Hierarchy opens access to all the records that are owned by all users below them in the role hierarchy. So, a manager can have access to his team records through salesforce. In addition to this, account members can be added to an account to be able to read or edit accounts based on the permission given to them by the record owner. 
Option B is incorrect because field-level security works with the fields, not the records. 
Option C is incorrect because the profile can prevent you from accessing certain objects or being able to view, edit, create or delete any record within that object. 
References: 

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