With no explanation, chose the best option from "A", "B", "C" or "D". 322 U.S. 665, 671, 64 S.Ct. 1240, 1243, 88 L.Ed. 1525 (1944). Mixed questions of law and fact are even more troubling for standard of review purposes. A mixed question is present when the facts are admitted or established and the law is undisputed; the sole issue is whether the law applied to the facts satisfies the statutory standard. Pullman-Standard v. Swint, 456 U.S. 273, 289, n. 19, 102 S.Ct. 1781, 1790, n. 19, 72 L.Ed.2d 66 (1982). Where the mixed question involves primarily a factual inquiry, the clearly erroneous standard is appropriate. If, however, the mixed question primarily involves the consideration of legal principles, then a de novo review by the appellate court is appropriate. See, e.g., United States v. McConney, 728 F.2d 1195, 1199-1205 (9th Cir.1984) (en banc) (<HOLDING>). Most appellate courts that have reviewed a

A: holding that antitrust standing is question of law reviewed de novo
B: recognizing that the constitutionality of a statute is a question of law subject to de novo review
C: holding that the question whether a party has agreed to submit an issue to arbitration is a question of law requiring de novo review
D: holding that the mixed question of exigent circumstance is reviewable de novo as a question of law
D.