Which of the following factors is responsible for the formation of concentrated urine ?

(A)Low levels of antidiuretic hormone.
(B)Maintaining hyperosmolarity towards inner medullary interstitium in the kidneys.
(C)Secretion of erythropoietin by juxtaglomerular complex.
(D)Hydrostatic pressure during glomerular filtration.

The NCERT line that answers it

Verbatim line

The proximity between the Henle's loop and *vasa recta*, as well as the counter current in them help in maintaining an increasing osmolarity towards the inner medullary interstitium, i.e., from $300 \text{ mOsmolL}^{-1}$ in the cortex to about $1200 \text{ mOsmolL}^{-1}$ in the inner medulla.

Chapter: Excretory Products and their Elimination
Section: 16.4 MECHANISM OF CONCENTRATION OF THE FILTRATE
Page: 7
Words matched: 21 of 21

The answer appears as a continuous sentence in NCERT. This is that sentence.

How this line gives the answer

0, emb=1.0, combined=1.0). Verified: high — The span explicitly states that the counter current mechanism 'help[s] in maintaining an increasing osmolarity towards the inner medullary interstitium', which directly matches option B's description of 'maintaining hyperosmolarity towards inner medullary interstitium'.

We did this for 1,565 questions.

Every one traced to the exact sentence in NCERT that answers it, including 90% of the 2026 paper. Sit a mock on the real NEET 2027 computer interface and every mark you drop comes back with its line attached.

Take the free 5-minute check More from this chapter

Question text is reproduced from the published NEET 2019 paper for study and commentary. NCERT text is quoted, not redistributed; textbooks remain at ncert.nic.in. Our mapping method, including its measured error rates, is published at /methodology.