The tubuloglomerular feedback is me­diated by:: (A) Sensing of Na+  concentration in the macula densa, (B) Sensing of HCO3 - concentration in macula densa, (C) Sensing NaCl concentration in the macula densa, (D) Opening up of voltage gated Na+ channels in afferent arteriole
Answer is C. Macula densa sense both Na+ and Cl- , but Cl- is more important.