You are designing your company's SQL Server 2000 sales database, which will be accessed by a custom application. Customer service and marketing employees require SELECT, INSERT, and UPDATE permissions on all tables in the Sales database. In addition to using the custom application, the marketing employees will use Microsoft Excel to retrieve data from the sales database to create charts.
Customer service employees belong to a Microsoft Windows 2000 group named CSR, and marketing employees belong to a Windows 2000 group named Marketing.
You want the customer service employees to access the sales database only from within the custom application.

You want to allow the marketing employees to use both the custom application and Excel to access the sales database.

No permissions have been granted in the database.
What should you do?

A. Create a database role named Marketing for the marketing employees and a database role named CustomerService for the customer service employees.
Add the Windows 2000 groups to the user-defined database roles.
Grant SELECT permissions on all tables in the database to the Marketing database role.
Grant SELECT, INSERT, and UPDATE permissions on all tables in the database to the
CustomerService database role.

B. Create one application role to be used by both the customer service and marketing employees.
Grant SELECT permissions on all tables in the database to the Windows 2000 Marketing group.
Grant SELECT, INSERT, and UPDATE permissions on all tables in the database to the Windows 2000 CSR group.

C. Create an application role for the custom application.
Grant SELECT, INSERT and UPDATE permissions to the application role. Create a database role named Marketing for the marketing employees.
Add the Windows 2000 Marketing group to the Marketing database role.
Grant SELECT permissions on all tables in the database to the Marketing database role.

D. Create one application role for the customer service employees.
Create a second application role for the marketing employees.
Grant SELECT permissions on all tables in the database to the application role to be used by the marketing employees.
Grant SELECT, INSERT, and UPDATE permissions on all tables in the database to the application role to be used by the customer service employees.

E. Create one application role for the customer service employees.
Create a second application role for the marketing employees to access the Sales database by using the custom application.
Create a third application role for the marketing employees to use when retrieving data from Excel.
Grant SELECT permissions on all tables in the database to both application roles to be used by the marketing employees.
Grant SELECT, INSERT, and UPDATE permissions on all tables in the database to the application role to be used by the customer service employees.

답은 C인데 컴퓨터 지식이 별로 없어서 잘 모르겠어요

문제도 해석도 정확히 안되고요 좀 도와주세요  ㅜ.ㅜ