Dina Asks Edie to Co-Sign a Credit Application So That

Dina asks Edie to co-sign a credit application so that she can borrow money and buy a piano from First Chair, a musical instruments and supplies seller. If, after the loan agreement is signed, Dina agrees to a higher rate of interest without telling Edie, then Edie is

A) discharged from the agreement.
B) liable at the higher rate of interest.
C) liable at the lower rate of interest.
D) liable for the principal only.