business law question

On April 1, 2008, Creese loaned $6,000 to Dasher in exchange for Dasher’s promise to make repayment, together with 8 percent interest, one year from that date.  (A) Suppose that on May 1 2008 Dasher pays $5000 cash to Creese, in return for Creese’s promise to cancel the entire debt.  May Creese claim anything more from Dasher?  (B) Suppose that on May 1, 2009 Dasher sent his check for $5000 to Creese, who cashed the check after seeing upon it the stipulation: “Payment in full of all debts owed by Dasher to Creese.”  May Creese claim anything more from Dasher?  (C) Suppose that on May 1, 2009 Dasher holds Cohick’s promissory note payable to Dasher in the sum of $5000, and then Dasher endorses and surrenders this note to Creese, in return for Creese’s promise to cancel the entire debt.  May Creese claim anything more from Dasher?