An administrator finds a new vulnerability in a web application and needs to rapidly mitigate the threat. Which F5 feature provides this functionality?

iCall is a scheduling and event framework used to trigger scripts or TMSH commands at specified times or system events, not to intercept or manipulate live traffic flows.

iRules allow administrators to write scripts that inspect, redirect, reject, or rewrite HTTP requests and responses on the fly without requiring a policy recompilation or device restart. This real-time programmability at the data plane makes iRules the primary F5 tool for rapid, targeted threat mitigation - a new rule can block a specific attack pattern within minutes of being written and applied to a virtual server.

iSession is an F5 WAN optimization feature that compresses and deduplicates traffic between BIG-IP devices and is entirely unrelated to web application security or threat mitigation.

iControl is the REST and SOAP management API used for programmatic configuration of BIG-IP, not for inline traffic inspection or real-time application-layer threat response.