X and Y have a contract which obligated X to sell Y 100 boxes of screws for $100. The parties orally midify the contract so that X will sell Y the same 100 boxes for $125. The 2nd agreement:
a. is not binding because it is oral
b. is not binding because x has only promised to perform a preexisting legal obligation
c. is not binding because it is an outputs contract
d. is binding
Facets of the oral contract are briefly listed.