Match List - I with List - II.

List - I	List - II
A. Heart B. Kidney C. Gastro-intestinal tracts D. Adrenal Cortex	I. Erythropoietin II. Aldosterone III. Atrial natriuretic factor IV. Secretin

Choose the correct answer from the options given below:

The correct option is A-III, B-I, C-IV, D-II.

To match List-I (Organs/Tissues) with List-II (Hormones), let's examine the physiological function and source of each hormone step-by-step:

A. Heart matches with III. Atrial natriuretic factor (ANF)
The atrial wall of the heart secretes a peptide hormone called Atrial Natriuretic Factor (ANF) when blood pressure increases. ANF causes dilation of blood vessels, which helps to decrease the blood pressure. Thus, A matches with III.

B. Kidney matches with I. Erythropoietin
The juxtaglomerular (JG) cells of the kidney produce a peptide hormone called erythropoietin. This hormone stimulates erythropoiesis, which is the process of formation of red blood cells (RBCs). Thus, B matches with I.

C. Gastro-intestinal tract matches with IV. Secretin
The endocrine cells present in different parts of the gastro-intestinal tract secrete several hormones, including secretin. Secretin acts on the exocrine pancreas and stimulates the secretion of water and bicarbonate ions. Thus, C matches with IV.

D. Adrenal Cortex matches with II. Aldosterone
The adrenal cortex (the outer region of the adrenal gland) secretes corticoids, one of the main mineralocorticoids being aldosterone. Aldosterone acts mainly at the renal tubules and stimulates the reabsorption of sodium ions and water. Thus, D matches with II.

Combining all the correct matches:
A - III
B - I
C - IV
D - II