Which of the Following Is False Regarding Joint Wills and Mutual

Which of the following is false regarding joint wills and mutual wills?

A) If two or more testators execute the same instrument as their will, the document is called a joint will.
B) A joint will may not be held invalid as to one testator but valid as to the other.
C) Mutual wills arise where two or more testators execute separate wills that make testamentary disposition of their property to each other on the condition that the survivor leave the remaining property on his or her death, as agreed by the testators.
D) Mutual wills are usually separate instruments with reciprocal terms.
E) Because of their contractual nature, mutual wills cannot be unilaterally revoked after one of the parties has died.