The correct answer is All of these reasons.

Continuous observation of the threat environment gives the security operations team the context they need to make informed decisions and to update defenses as adversaries change tactics. This activity supports To guide risk management and prioritize security controls, it supports To discover new and evolving attack techniques, and it supports To ensure systems are not exposed to known exploits. Together these benefits explain why All of these reasons is the right choice.

To guide risk management and prioritize security controls is a valid motivation because monitoring reveals which assets and vulnerabilities present the highest current risk and where defensive resources should be applied. It is not wrong but it is only one piece of the overall need to monitor threats.

To discover new and evolving attack techniques is also important because detection and threat hunting rely on knowing how attackers operate. This reason alone does not capture the full operational need to prioritize and remediate risks though.

To ensure systems are not exposed to known exploits describes the remediation and hardening side of monitoring. It is essential practice but it is only a single outcome of continuous observation rather than the complete justification.

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