Users Require Access Rights That Allow Them to View the Average

Users require access rights that allow them to view the average salary of groups of employees. Which control would prevent the users from obtaining an individual employee's salary?

A) Limit access to predefined queries
B) Segregate the database into a small number of partitions each with a separate security level
C) Implement Role Based Access Control (RBAC)
D) Reduce the number of people who have access to the system for statistical purposes