Directions: Choose the one that best fits into the abstract from the four choices marked A, B, C or D. Intake of vitamin D and risk of type 1 diabetes: a birth-cohort study Summary Background Dietary vitamin D supplementation is __1__ with reduced risk of type1 diabetes in animals. Our aim was to _2__ whether or not vitamin D supplementation or deficiency in infancy could affect __3__of type 1 diabetes. Methods A birth-cohort study was __4__, in which all pregnant women (n=12055) in Oulu and Lapland, northern Finland , who were due to give birth in 1966 were __5__ . Data was __6__ in the first year of life _7___ frequency and dose of vitamin D supplementation and __8__ of suspected rickets. Our __9__ outcome measure was diagnosis of type 1 diabetes by end of December, 1997. Findings 12058 of 12231 represented live births, and 10821 (91% of those alive) children were followed-up at age 1 year. Of the 10366 children included in analyses, 81 were diagnosed with diabetes during the study. Vitamin D supplementation was associated with a decreased frequency of type 1 diabetes when adjusted for neonatal, anthropometric, and social characteristics (rate ratio [RR] for regular __10__ no supplementation 0.12, 95% CI 0.03-0.51, and irregular versus no supplementation 0.16, 0.04-0.74. Children who regularly took the __11__ dose of vitamin D (2000 IU daily) had a RR of 0.22 (0.05-0.89) __12__ with those who regularly received less. Children __13__ of having rickets during the first year of life had a RR of 3.0(1.0-9.0) as opposed to those without such a suspicion. Interpretation Dietary vitamin D supplementation is associated with reduced risk of type 1 diabetes. Ensuring adequate vitamin D supplementation for infants could help to __14__ the increasing trend in the __15__ of type 1 diabetes.