A consultant is hired to do physical penetration testing at a large financial company. In the first day of his assessment, the consultant goes to the company`s building dressed like an electrician and

A man trap is a physical security countermeasure consisting of a small room with two interlocked doors, not an attack technique performed by an intruder.

Tailgating is a physical intrusion technique where an unauthorized person gains access to a restricted area by closely following an authorized individual through a secured entry point. The consultant exploited the natural human tendency to hold doors open or allow others to pass, bypassing the access control entirely. No deception of identity or credentials was required - only physical proximity to an authorized user.

Shoulder surfing involves observing someone's screen, keyboard, or PIN entry to steal information, not physically following someone through a door.

Social engineering is a broad category of manipulation-based attacks; tailgating is the specific physical technique used here, making B the more precise and correct answer.