Option 1 -> Tarnish means to damage or spoil the quality of something, not to reject it.
Option 2 -> Embrace means to accept or support willingly, which is the opposite of repudiate.
Option 3 -> Decline means to refuse or reject something, closely aligned with repudiate.
Option 4 -> Endorse means to approve or support, which is also opposite to repudiate.
Hence, Option 3: Decline -> "Repudiate" means to refuse to accept, reject, or disown something, and "decline" shares this meaning of refusing or rejecting -> correct