The first step in the renin-angiotensin mechanism is:

A)angiotensin II circulates to the adrenal cortex, stimulating the secretion of aldosterone.
B)renin causes angiotensinogen to be converted to angiotensin I.
C)the juxtaglomerular apparatus secretes renin into the blood in response to a fall in the blood pressure within the kidney.
D)aldosterone causes increased reabsorption of sodium, which causes increased water retention.