Answer:A. Reconstitute the system
Explanation:A Rootkit is a combination of malicious softwares which are used by Hackers to steal previledged information or data from a system. This Hackers usually make use of Keyloggers, antivirus disablers, password disablers to prevent a person or an organization to have access to its system. It has been established that after a Rootkit the only advisable action is to Reconstitute the system, reconstitution will enable you to wipe out all system information and start all over to input new details.