(a) A claim or part of a claim that has been rejected by the guardian of the estate is barred unless not later than the 90th day after the date of rejection the claimant commences suit on the claim in the court of original probate jurisdiction in which the guardianship is pending or in any other court of proper jurisdiction.
(b) In a suit commenced on the rejected claim, the memorandum endorsed on or attached to the claim is taken to be true without further proof unless denied under oath.