The degree to which a control's implementation is expected to change over time is correct.

Control volatility refers to how much a safeguard is expected to change as technologies, business processes, or threat landscapes evolve. That phrasing matches the idea of an expected degree of change in the control itself rather than a single error or a measured probability.

Misconfigured Cloud IAM policies that permit unintended access is incorrect because that option describes a specific misconfiguration or vulnerability and not the general concept of how a control is expected to change over time.

The probability that configuration drift will cause a control to become noncompliant is incorrect because it frames the issue as a likelihood or probability. Volatility concerns the expected degree of change or churn in the control, not the probability that drift will lead to noncompliance.

The risk that changes in the system or its external environment will render a control ineffective is incorrect because it describes an outcome or risk from changes rather than the expected rate or degree of change in the control's implementation. Volatility is about expected change itself and not directly about the resulting risk of ineffectiveness.

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