The neonatal kidney achieves concentrating ability equivalent to adult's kidney by:
Answer is A (One year of age) : "Normal adult kidney can produce urine with an osmolalitv of greater than 1000 m Osm/kg water. The healthy new born infant, subject to water deprivation for 10-14 hours can achieve an osmolality of only 500-700 m osm / kg. This value increases gradually during the first few months and approximates to the adult value by about one year of age."
One year of age
Eighteen months of age
Three to six months of age
Just before pubey