The correct answer is 'Likeness,' as it involves establishing a rapport or a sense of commonality with the target. Understanding this principle is essential because people tend to respond favorably to those whom they perceive as similar to themselves, which can be exploited by attackers. 'Reciprocity' is incorrect as it refers to the obligation to return a favor. While 'Social proof' is incorrect because it's about the influence of seeing others performing the behavior, and 'Consistency' is about people's desire to be consistent with what they have previously said or done.