Final answer:
Angiotensin II is the substance that induces renin secretion, constricts afferent arterioles, and reduces GFR and urine volume. It is a vasoconstrictor that works as part of the body's mechanism to elevate blood pressure and conserve fluids.
Step-by-step explanation:
The question asks which of the following options induces renin secretion, constricts afferent arterioles, reduces Glomerular Filtration Rate (GFR), and decreases urine volume. The correct answer to this question is Angiotensin II. Renin, secreted by the juxtaglomerular complex, acts on angiotensinogen to form angiotensin I, which is then converted to angiotensin II by Angiotensin-Converting Enzyme (ACE). Angiotensin II is a powerful vasoconstrictor that narrows blood vessels, including the afferent arterioles of the kidney, thereby reducing GFR and urine volume. It also stimulates aldosterone and Antidiuretic Hormone (ADH) release, which help to stabilize blood pressure and volume by enhancing sodium and water retention in the kidneys.