To "usurp" power means to:

To "usurp" power refers specifically to taking control or authority over something, particularly in a forceful or unlawful manner. This term suggests that the individual seizing power does so without the right or legal basis to do so, making it an act of taking rather than a legitimate acquisition. Historically, usurpation often involves overthrowing someone in a position of authority, such as a ruler or leader, and it is associated with acts that challenge established systems and rights.

The other options describe scenarios that are fundamentally different from usurpation. Gaining power legitimately implies adherence to rules and norms, conferring authority suggests granting permissions or rights to someone else, and resigning gracefully connotes relinquishing power voluntarily and often with respect. In contrast, usurpation is inherently a conflict-driven act that disrupts existing authority.