Choice "A" is correct. Signing without recourse negates contract liability on the instrument. Contract liability is the promise to pay upon dishonor. UCC 3-414
Choice "d" is incorrect. An endorser is liable to subsequent parties on an instrument; not to prior parties, and this is true no matter how the endorser signs.
Choice "b" is incorrect. Signing without recourse negates contract liability on the instrument. Warranty liability (e.g., all signatures are genuine, the instrument has not been materially altered, etc.) is not negated.
Choice "c" is incorrect. A person does not automatically convert a check to order paper by endorsing it "without recourse." A special endorsement (i.e., one naming a new payee) can convert bearer paper to order paper.