Which of the following solutions provides the most flexibility when testing new security controls prior to implementation?

A.
Trusted OS

B.
Host software baselining

C.
OS hardening

D.
Virtualization

Explanation:
Virtualization is used to host one or more operating systems in the memory of a single host computer and allows multiple operating systems to run simultaneously
on the same hardware. Virtualization offers the flexibility of quickly and easily making backups of entire virtual systems, and quickly recovering the virtual system
when errors occur. Furthermore, malicious code compromises of virtual systems rarely affect the host system, which allows for safer testing and experimentation.
Incorrect Answers:
A: Trusted OS is an access-control feature that limits resource access to client systems that run operating system that are known to implement specific security

features.
B: Application baseline defines the level or standard of security that will be implemented and maintained for the application. It may include requirements of
hardware components, operating system versions, patch levels, installed applications and their configurations, and available ports and services. Systems can be
compared to the baseline to ensure that the required level of security is being maintained.
C: Hardening is the process of securing a system by reducing its surface of vulnerability. Reducing the surface of vulnerability typically includes removing or
disabling unnecessary functions and features, removing or disabling unnecessary user accounts, disabling unnecessary protocols and ports, and disabling
unnecessary services.

Dulaney, Emmett and Chuck Eastton, CompTIA Security+ Study Guide, Sixth Edition, Sybex, Indianapolis, 2014, pp 215-217
Stewart, James Michael, CompTIA Security+ Review Guide, Sybex, Indianapolis, 2014, pp 37, 208, 246