For a valuable consideration, Amato, the owner of Riveracre, signed and gave to Barton a duly executed instrument that provided as follows: "The grantor may or may not sell Riveracre during her lifetime, but at her death, or if she earlier decides to sell, the property will be offered to Barton at $500 per acre. Barton shall exercise this right, if at all, within 60 days of receipt of said offer to sell." Barton recorded the instrument. The instrument was not valid as a will. Is Barton's right under the instrument valid?
Yes, because the instrument is recorded.  Yes, because Barton's right to purchase will vest or fail within the period prescribed by the Rule Against Perpetuities.  No, because Barton's right to purchase is a restraint on the owner's power to make a testamentary disposition.  No, because Barton's right to purchase is an unreasonable restraint on alienation