Which of the following statements about aldosterone is not correct?

a. aldosterone increases the number of passive sodium channels in the luminal membrane of the distal tubule and collecting duct, thus aiding sodium reabsorption.
b. aldosterone is produced in the adrenal cortex.
c. aldosterone increases sodium reabsorption by increasing the number of na+-k+ atpase pumps in the luminal membrane of the proximal tubule.
d. aldosterone is stimulated by decreased plasma sodium levels and increased plasma potassium levels.