What Is the Attestation Clause for Wills

What is the attestation clause for wills?

A) the condition that the witness must reside in the jurisdiction in which the testator is domiciled
B) the stipulation that only the testator's attorney can be a witness to the will
C) the requirement of signatures of witnesses on a will after that of the testator's
D) the requirement of the beneficiary's presence when making the will