The key element for effective interpersonal communication is

Active listening is the key element here. It means hearing the speaker fully, without rehearsing your reply, and then checking your understanding by paraphrasing or asking a clarifying question. Carl Rogers and later communication theorists treat it as the base of empathetic, two-way exchange, because people only open up when they feel heard.

Why the others fail:

• Abstraction is a barrier, not a tool. Words are general symbols that carry different meanings for different listeners, so meaning drifts unless it is grounded in specifics.
• De-sensitization means losing sensitivity to others' feelings. That weakens communication, and it is the opposite of what the question asks for.
• Ego-centric reinforcement keeps the focus on oneself. It turns a conversation into a monologue and blocks feedback.

Mains angle: this links to emotional intelligence in GS IV, especially empathy and active listening in public service roles like grievance redressal.

Trap: aspirants pick 'Abstraction' because it sounds sophisticated; remember that in communication theory it is listed as a barrier.