A company has two departments: Sales and Operations. The Sales department divides its salespeople into East, West, and Central teams. The Operations department has two groups: Accounting and Engineering. The company asks you to help with the security model for their departments. The company has the following requirements: The Accounting manager needs to have access to the data of all departments.
The Sales manager must have access to all sales data and read-only access to Engineering data.
What security model for the Dataverse records access will you propose to implement?

Answer options:

A.Hierarchical
B.Organization
C.Business units
D.Teams
E.Azure AD groups

Correct Answer: C 
The Business unit security model is the basis for Dataverse security. The model controls access to the data using security roles, teams, and users. By linking all of them together, you are getting a role-based security model. By default, the Organization is a top-level of a business unit hierarchy. Each business unit has a default team. You cannot change or delete the default team. You must assign every user to only one business unit. 
The business unit security model uses security roles to assign them to the users or teams. A team also can consist of users from different business units.
Option A is incorrect because the Hierarchical security model is based on who reports to whom. According to this model, the user can have read and write access to the data of the people who report to the user. And the reportees have access to the data of people who report to them, etc. In this task, the security model is defined by the business unit’s boundaries.
Option B is incorrect because the Organization is a privilege access level. This role can view all accounts in all business units of the organization. The access level is a part of the security model, but it is not a security model.
Option D is incorrect because the Teams is a grouping of the users that you can assign the security roles to. The teams are part of a security model, but they are not a security model.
Option E is incorrect because the Azure AD groups are one of the Teams types, but it is not a security model.
For more information about Dataverse business unit’s security, please visit the below URLs: 

https://docs.microsoft.com/en-us/learn/modules/model-security/4-dataverse
https://docs.microsoft.com/en-us/power-platform/admin/create-edit-business-units
https://www.youtube.com/watch?v=8UWSj-vvxzU