Explanation/Reference:
Explanation:
To run a source comparison does not prevent any specific action from occurring.
Security controls are safeguards or countermeasures to avoid, detect, counteract, or minimize security risks to physical property, information, computer systems, or other assets. Controls help to reduce the risk of damage or loss by stopping, deterring, or slowing down an attack against an asset.
To help review or design security controls, they can be classified by several criteria, for example according to the time that they act, relative to a security incident:
Before the event, preventive controls are intended to prevent an incident from occurring e.g. by locking

out unauthorized intruders;
During the event, detective controls are intended to identify and characterize an incident in progress

e.g. by sounding the intruder alarm and alerting the security guards or police; After the event, corrective controls are intended to limit the extent of any damage caused by the

incident e.g. by recovering the organization to normal working status as efficiently as possible.
Incorrect Answers:
A: Denying a programmer access to production data is an example of preventive control as it prevents the programmer from accessing the data.
B: To make a change request to include extra information would prevent unauthorized changes from being made.
D: By establishing procedure for emergency changes unauthorized changes could be prevented.
References:
https://en.wikipedia.org/wiki/Security_controls