What do operational testers evaluate to determine the degree to which a system is usable in its intended environment, e.g., reliable, supportable, maintainable, and transportable?

Question
What do operational testers evaluate to determine the degree to which a system is usable in its intended environment, e.g., reliable, supportable, maintainable, and transportable?
None of the answers are correct
Measures of Suitability (MOS)
Measures of Effectiveness (MOE)
Critical Technical Parameters (CTP)

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