Which of the following is an example of osmosis?
a. water leaves the tubules of the kidney due to hypertonic fluid surrounding the tubules.
b. digestive enzymes are excreted into the small intestine.
c. white blood cells consume pathogens at the site of an infection.
d. calcium is pumped inside a muscle cell after the muscle cell completes its contraction.

The correct answer is option A, that is, water leaves the tubules of the kidney due to hypertonic fluid surrounding the tubules.

Explanation:

Osmosis refers to a procedure by which the solvent molecules seem to go via a semipermeable membrane from a less concentrated solution into a more concentrated solution, thus equalizing the concentrations on both sides of the membrane.  

In the given question, an illustration of osmosis is when the water leaves the tubules of the kidney in response to the hypertonic fluid enveloping the tubules. In the kidneys, osmosis is a filtration. In the kidneys, osmosis will filter the molecules of water and solutes from the plasma to the tubules.  

the answer is :

c. the initial amount of money placed in the savings account