Calcitriol in children is formed in:

Ans: C (PCT) 25-hydroxyvitamin D3 - Calcitriol (1,25-hydroxyvitamin D3) by la- hydroxylase in PCT- AK Jain 5th/730; O.P.Ghai 8th/112"Calcitriol is produced in the cells of the proximal tubule of the nephron in the kidneys by the action of 25-hydroxyvitamin D3 1-alpha-hydroxylase, a mitochondrial oxygenase and an enzyme which catalyzes the hydro.vylation of 25-hydroxycholecal- ciferol (caicifediol). The activity of the enzyme is stimulated by PTH. The reaction is an important control point in Ca2+ homeostasis"- https://en.wikipedia.arg/wik/Calcitriol