In PingAccess, auditing is configured on a per-resource basis. To capture all access requests for a specific resource, such as /admin, the most direct and appropriate method is to enable the "Audit" option within the configuration settings for that particular resource. This setting instructs the PingAccess engine to generate an audit log entry for every policy evaluation related to that resource path, providing granular control over what is logged. This approach is precise and avoids generating unnecessary log entries for other resources.

B. Enabling the Audit option for the / resource is incorrect because it is too broad. This would capture audit events for all resources, not just the /admin resource as specified in the requirement.

C. Splunk is a log aggregation and analysis tool, a potential destination for logs. The generation of the audit event itself must first be configured within PingAccess, not in the external logging system.

D. The log4j2.xml file configures the logging framework's behavior, such as log levels, formats, and appenders (destinations). It does not control the application-level policy decision of which specific resources to audit.

1. PingAccess 7.3 Administrator's Guide, Section: "Defining resources". The documentation details the configuration fields available when creating or editing a resource. It explicitly lists an "Audit" checkbox with the description: "Select this check box to log all access attempts to this resource in the audit log." This confirms that auditing is a specific setting on the resource itself.

2. PingAccess 7.3 Administrator's Guide, Section: "Configuring audit logging". This section describes how to configure the destination for audit logs (e.g., file, syslog, Splunk) via the log4j2.xml file, but it clarifies that the decision to audit a request is made at the application/resource policy level, not within the logging framework configuration. This distinguishes the roles of resource configuration (Option A) from logging infrastructure configuration (Options C and D).