Select the correct statement:

The juxtaglomerular cells ($JGC$) secretes an enzyme rennin in response to a variety of stimuli such as decreased flow of filtrate and $NaCl$ to macula densa, decrease in glomerular filtration rate ($GFR$), decreased stretch of $JGC$, and increased frequency of nerve impulses in the renal sympathetic nerves.

Atrial Natriuretic Factor ($ANF$) decreases blood pressure as it is a powerful vasodilator.

Angiotensin $II$ is a powerful vasoconstrictor.

The counter-current mechanism involves the exchange of water and electrolytes between blood flowing in vasa recta and filtrate in Loop of Henle.