Choice "C" is correct. Striking a prior endorser discharges the endorser's liability to all persons who take the instrument after the signature is stricken. UCC 3-601
Choice "d" is incorrect. Striking a prior endorser discharges the endorser's liability to all persons who take the instrument after the signature is stricken. It has no effect on a prior endorser's liability because liability goes up the chain of title. UCC 3-601
Choice "b" is incorrect. Striking a prior endorser discharges the endorser's liability to all persons who take the instrument after the signature is stricken. It has no effect on a prior endorser's liability because liability goes up the chain of title. UCC 3-601
Choice "a" is incorrect. Striking a prior endorser discharges the endorser's liability to all persons who take the instrument after the signature is stricken. It has no effect on a subsequent endorser's own liability.