A person may assert a claim in a specified foreign money. If a foreign-money claim is not asserted, the claimant makes the claim in United States dollars. An opposing party may allege and shall prove that all or part of a claim is in a different money than that asserted by the claimant. A person may assert a defense, setoff, recoupment, or counterclaim in any money without regard to the money of other claims. The determination of the proper money of the claim is a question of law.