Which form is used to obtain a tax identification number for the estate? Question 11 options: 1) U.S. Treasury Form 706, U.S. Estate (and Generation-Skipping Transfer) Tax Return 2) Form SS-4, Application for an Employer Identification Number 3) Form 4768, Application for Extension of Time to File U.S. Estate Tax Return 4) Form 56, Notice Concerning Fiduciary Relationship