True about Macula Densa is/are:: (A) Also known as Tubulo glomerular feedback., (B) Macula densa senses change in NaCl concentration., (C) For autoregulation of GFR., (D) All of the above.
Answer is D. Function of Macula Densa (Tubulo glomerular feedback): 

Macula densa senses change in NaCl concentration. 
For autoregulation of GFR.