A deficiency of which one of the listed enzymes is most likely to be associated with the formation of multiple pale yellow, hard, round stones within the gallbladder?

Gallstones, which affect 10 to 20% of the adult population in developed countries, are divided into two main types. Cholesterol stones are pale yellow, hard, round, radiographically translucent stones that are most often multiple. Their formation is related to multiple factors including female sex hormones (such as with oral contraceptives), obesity, rapid weight reduction, and hyperlipidemic states. Their prevalence approaches 75% in some Native American populations. 7-a-hydroxylase is an enzyme involved in conveing cholesterol to bile acids. Decreased functioning of this enzyme, such as with a congenital deficiency or inhibition by clofibrate, causes excess secretion of cholesterol and an increased incidence of cholesterol gallstones. The other main type of gallstones are pigment stones, which are brown or black in color and composed of bilirubin calcium salts. They are found more commonly in Asian populations and are related to chronic hemolytic states, diseases of the small intestines, and bacterial infections of the biliary tree. In contrast to 7-a-hydroxylase and bile acid synthesis, 1-a-hydroxylase is involved in vitamin D synthesis, while 11-hydroxylase, 17-hydroxylase, and 21- hydroxylase are all enzymes found in the adrenal coex. A deficiency of these enzymes is seen with congenital adrenal hyperplasia Reference: Robbins & Cotran Pathologic Basis of Disease, 9edition