Which enzyme converts angiotensinogen into angiotensin-$I$?

What is the primary function of $ADH$?

What is $RAAS$?

Osmoreceptors in the body are activated by changes in:
$I.$ blood volume
$II.$ body fluid volume
$III.$ ionic concentration
Which of the following options contains the correct statements?

Select the correct option with respect to the following statements:
$(a)$ Angiotensin $II$ constricts arterioles in the kidney to reduce blood flow and decreases blood pressure when blood flow to the afferent arteriole decreases.
$(b)$ Angiotensin $II$ stimulates the adrenal cortex to release aldosterone for more absorption of $Na^+$ and $Cl^-$ ions in the $DCT$.
$(c)$ Blood osmolarity varies with the secretion of aldosterone and $ANP$.

Which one is the vasoconstrictor?