When querying a database for statistical information, individually identifiable information should be protected. Thus, requiring a minimum size for the query set (greater than one) offers protection against gathering information on one individual. However, an attack may consist of gathering statistics on a query set size M, equal to or greater than the minimum query set size, and then requesting the same statistics on a query set size of M + 1. The second query set would be designed to include the individual whose information is being sought surreptitiously.
*Thus with answer "Specifying a minimum query set size, but prohibiting the querying of all but one of the records in the database", this type of attack could not take place.
* Answer "Specifying a minimum query set size" is, therefore, incorrect since it leaves open the loophole of the M+1 set size query. Answers "Specifying a maximum query set size" and "Specifying a maximum query set size, but prohibiting the querying of all but one of the records in the database" are incorrect since the critical metric is the minimum query set size and not the maximum size. Obviously, the maximum query set size cannot be set to a value less than the minimum set size.

The questions specifically said: "within a different function" which eliminate Job
Rotation as a choice.
Management monitoring of audit logs is a detective control and it would not prevent collusion.
Changing passwords regularly would not prevent such attack.
This question validates if you understand the concept of separation of duties and least privilege.
By having operators that have only the minimum access level they need and only what they need
to do their duties within a company, the operations personnel would be force to use collusion to
defeat those security mechanism.
Source: TIPTON, Hal, (ISC)2, Introduction to the CISSP Exam presentation.