Metasploit's Auxiliary modules are designed for tasks that do not include exploitation, and scanning is one of the primary functions of these modules. They can be used to perform a variety of actions such as scanning for vulnerabilities, gathering information, and conducting various types of network reconnaissance. Exploit modules are used specifically for taking advantage of vulnerabilities, Post modules are utilized after an exploit has been successful, and Payload modules deliver the payload that will be executed on the target system. Hence, Auxiliary is the correct answer.