Which of the following is NOT sufficient to revoke an entire prior will?

a. The valid execution of a subsequent will which states that all prior wills are revoked.

b. The valid execution of a codicil which expressly revokes all prior wills.

c. The intentional defacing of a prior will.

d. The execution of a codicil which changes one article from your first will leaving your beach house to your daughter instead of your son.