Kelly Contracts with Raphael for Raphael to Bring a Pony

Multiple Choice

Kelly contracts with Raphael for Raphael to bring a pony to her daughter's birthday party in exchange for $100.Kelly later learns her daughter is frightened of ponies.She contacts Raphael and Raphael agrees to bring a donkey to the party for $50 instead.Which of the following is true of the original agreement involving the pony and the $100?

A) It was discharged by novation
B) It was discharged by accord and satisfaction
C) It was breached
D) It was discharged by mutual rescission
E) It was discharged by substituted contract