A penetration tester harvests potential usernames from a social networking site. The penetration tester then uses social engineering to attempt to obtain associated passwords to gain unauthorized…

Escalation of privilege occurs after initial access has been gained, when an attacker attempts to obtain higher-level permissions, which is not what the scenario describes.

SQL injection is a web application vulnerability exploitation technique used to manipulate database queries, which is unrelated to the social engineering and information gathering described.

Active reconnaissance involves directly interacting with the target system or personnel to gather information, such as harvesting usernames from social media and using social engineering to obtain passwords, all in preparation for an attack. These actions directly engage with the target to collect data for gaining unauthorized access.

A proxy server acts as an intermediary for network requests and, while potentially used during an attack, does not describe the method of information gathering or credential harvesting itself.