Answer:
Check explanation section.
Step-by-step explanation:
Prisons are built in order to minimize threats in the society and also to correct offenders by making sure that are taken away from people that they care about and isolating them so that they can become a better being when they come out(correctional center).
In correctional center, the term internal security is used for the trained staffs that are making sure the offenders are barred from seeing people from outside the correctional centres. Internal security officers are being trained on how to use external securities.
External security are securities such as alarm, iron bars/high fences, cameras for surveillance and many more. External securities are tools used in making sure that offenders stays in the confined environment.