Please select the eligibility criteria that correspond to the clinical trial below.
Title: Vitamin D Dose-Response Study to Establish Dietary Requirements in Infants
Brief Summary: The research team is comprised of an expert nutrition scientist and a pediatrician with expertise in endocrinology. Both have world-class experience in assessing bone mass in infancy. Together they have designed a study to determine how much dietary vitamin D is needed to optimize health in infants. This is important since many infants are born with vitamin D deficiency. At present the dosage of vitamin D that is optimal for infant health is unclear and recent research suggests that vitamin D status very early in life has long lasting effects on bone mass and other health issues. Therefore, in a group of healthy infants, this research team will test which dosage of vitamin D is needed to achieve optimal vitamin D status. Optimal vitamin D status will be based on growth, biomarkers of vitamin D and bone status in blood and also general health. The infants will all be breastfed and begin the study at about 2 weeks of age. At 3 months intervals over the first year of life, each infant will be measured for growth, duration of breastfeeding and supplement use plus have a bone density scan to determine changes in bone growth. The data will be helpful to guide health care professionals in providing the best care possible for their infants. It will also be important to the health of populations since dietary recommendations for vitamin D are used to guide fortification of foods and development of evidence based policy around nutrient recommendations and their implementation.


Options:
A: Inclusion Criteria:

* Healthy singleton term born infants of appropriate size for gestational age (AGA) according to the Centers for Disease Control growth charts based on weight at birth between the 5th and 95th percentiles for sex; and born to healthy breastfeeding women. This allows us to assess growth and bone mineral accretion without bias of intrauterine growth restriction.

Exclusion Criteria:

* Infants of mothers with history of gestational diabetes or hypertension in pregnancy; chronic alcohol use; malabsorption syndromes due to malabsorption of vitamin D (celiac disease, Crohn's etc.); and multiple births.
* Should any exclusion criteria be identified after recruitment, the infant will be excluded from the main analyzes, but followed in a separate arm as intent-to-treat.
B: Inclusion Criteria:

* Born at term, as determined from last menstrual period
* Weighing \< 2.5 kg
* Resident within 12 km of the hospital and expected to continue living in the area for the following 6 months
* With no severe congenital abnormalities
* No morbidity severe enough to be expected to result in death before 7 days due to severe respiratory distress, shock, pulmonary sepsis, etc.
* Parental informed consent
C: Inclusion Criteria:

1. 1 to 11 month old infants living in the study area
2. caretakers are willing to give consent to take part in the study

Exclusion Criteria:

1. the family is likely to migrate out of the study area within the next 18 months
2. the child has been diagnosed with rickets or known to have received a course of vitamin D treatment in the past 3 monDths.
3. Child with Kwashiorkor or Marasmus.
D: Inclusion Criteria:

* Eligible subjects will be children age 12 to 15 years inclusive in public school, located in Songino-Khairhan district, who are residents of Ulaanbaatar, and whose parents have given informed consent and who accent to participate in the study.

Exclusion Criteria:

* Individuals with pre-existing calcium, parathyroid conditions, or type I diabetes, sarcoidosis, or who require chronic diuretic therapy including calcium channel blockers, or who are cognitively impaired.

Answer: A