The process of making certain that an entity (operating system, application, etc.) is as secure as it can be is known as:

A.
Stabilizing

B.
Reinforcing

C.
Hardening

D.
Toughening

Explanation:
Hardening is the process of securing a system by reducing its surface of vulnerability. Reducing the surface of vulnerability typically includes removing unnecessary
functions and features, removing unnecessary usernames or logins and disabling unnecessary services.
Incorrect Answers:
A, B, D: The correct term for making a system as secure as possible is hardening, not stabilizing, reinforcing, or toughening.

Dulaney, Emmett and Chuck Eastton, CompTIA Security+ Study Guide, Sixth Edition, Sybex, Indianapolis, 2014, pp 215-217