The policy set that should be used to ensure that a policy is applied just before the default security rules is the shared post-rulebase. The shared post-rulebase is a set of Security policy rules that are defined on Panorama and apply to all firewalls or device groups. The shared post-rulebase is evaluated after the local firewall policy and the child device-group post-rulebase, but before the default security rules. The shared post-rulebase can be used to enforce common security policies across multiple firewalls or device groups, such as blocking high-risk applications or traffic1. References: Security Policy Rule Hierarchy, Security Policy Rulebase, Certifications - Palo Alto Networks, Palo Alto Networks Certified Network Security Administrator (PAN-OS 10.0) or [Palo Alto Networks Certified Network Security Administrator (PAN-OS 10.0)].

Explanation
Reconnaissance - stage where the attacker scans for network vulnerabilities and services that can be exploited.
Installation - stage where the attacker will explore methods such as a root kit to establish persistence Command and Control - stage where the attacker has access to a specific server so they can communicate and pass data to and from infected devices within a network.
Act on the Objective - stage where an attacker has motivation for attacking a network to deface web property

Policy Optimizer provides a simple workflow to migrate your legacy Security policy rulebase to an App-ID based rulebase, which improves your security by reducing the attack surface and gaining visibility into applications so you can safely enable them. Policy Optimizer can also identify unused rules, duplicate rules, and rules that can be merged or reordered to optimize your rulebase. You can use Policy Optimizer to review the usage statistics of your rules and take actions to clean up or modify your rulebase as needed1. Reference: Security Policy Rule Optimization, Updated Certifications for PAN-OS 10.1, Free PCNSE Questions for Palo Alto Networks PCNSE Exam