With no explanation, chose the best option from "A", "B", "C" or "D". under 11 U.S.C. § 550. If the District of Columbia Court of Appeals holds that a dissolved firm has a property interest in the profits earned from ongoing client matters billed on an hourly basis, we will remand to the district court for an assessment, in the first instance, of whether the defendant firms are liable as subsequent transferees under the fraudulent transfer provisions of the bankruptcy code, 11 U.S.C. §§ 548 and 550. We believe that the answers to the questions we present are important for D.C. attorneys and their clients. Because these issues are substantive, and affect the outcome of the litigation, they should be resolved in accord with the substantive law of the District of Columbia, See Erie R. Co. v. Tompkins, 304 U.S. 64, 78, 58 S.Ct. 817, 82 L.Ed. 1188 (1938) (<HOLDING>); Guaranty Trust Co. v. York, 326 U.S. 99

A: holding that a federal court in diversity jurisdiction must apply state substantive law
B: holding that federal courts sitting in diversity shall apply state substantive law
C: holding that federal courts sitting in diversity should apply state law that determines the outcome of the case
D: holding that in diversity cases federal courts are to apply state substantive law and federal procedural law
B.