A key risk indicator (KRI) is a metric that provides an early warning of potential exposure to a risk. A KRI should be relevant, measurable, timely, and actionable. The most important factor in an organization's selection of a KRI is the criticality of information, which means that the KRI should reflect the value and sensitivity of the information assets that are exposed to the risk. For example, a KRI for data breach risk could be the number of unauthorized access attempts to a database that contains confidential customer data. The criticality of information helps to prioritize the risks and focus on the most significant ones. References:
https://www.isaca.org/credentialing/cism https://www.wiley.com/en-us
/CISM+Certified+Information+Security+Manager+Study+Guide-p-9781119801948

Senior leadership needs to understand how Zero Trust supports risk reduction and business needs.
Communicating the impact on risk reduction and user experience aligns security initiatives with business goals.
"Communicating how security initiatives support business objectives and risk reduction is critical for gaining senior management support."
- CISM Review Manual 15th Edition, Chapter 1: Information Security Governance, Section: Business Alignment*

An effective information security awareness training program should aim to improve the knowledge, skills and behavior of the employees regarding information security. One of the ways to measure the effectiveness of such a program is to conduct phishing simulations, which are mock phishing attacks that test the employees' ability to identify and report phishing emails. An increase in the identification rate during phishing simulations indicates that the employees have learned how to recognize and avoid phishing attempts, which is one of the common threats to information security. Therefore, this is the best indication of an effective information security awareness training program among the given options.
The other options are not as reliable or relevant as indicators of an effective information security awareness training program. An increase in the frequency of phishing tests does not necessarily mean that the employees are learning from them or that the tests are aligned with the learning objectives of the program. An increase in positive user feedback may reflect the satisfaction or engagement of the employees with the program, but it does not measure the actual learning outcomes or behavior changes. An increase in the speed of incident resolution may be influenced by other factors, such as the availability and efficiency of the incident response team, the severity and complexity of the incidents, or the tools and processes used for incident management.
Moreover, the speed of incident resolution does not reflect the prevention or reduction of incidents, which is a more desirable goal of an information security awareness training program. References = CISM Review Manual, 16th Edition, ISACA, 2022, pp. 201-202, 207-208.
CISM Questions, Answers & Explanations Database, ISACA, 2022, QID 1001.