K+ excretion is markedly influenced by :a) aldosteroneb) amount of Na+ delivered to tubulesc) rate of tubular secretion of H+d) all of the above .

The correct answer is d) all of the above.

Here's why:

a) Aldosterone: This hormone plays a crucial role in regulating potassium levels in the body. It does this by promoting the excretion of potassium into the urine by the kidneys.

b) Amount of Na+ delivered to tubules: The amount of sodium that reaches the renal tubules can influence potassium excretion. This is because sodium reabsorption in the renal tubules is coupled with potassium secretion. Therefore, the more sodium that is delivered to the tubules, the more potassium is likely to be excreted.

c) Rate of tubular secretion of H+: The kidneys also regulate the body's pH by varying the rate of hydrogen ion (H+) secretion. Changes in the rate of H+ secretion can influence potassium excretion because H+ and K+ compete for secretion in the renal tubules. Therefore, an increase in H+ secretion can lead to a decrease in K+ secretion, and vice versa.