Final answer:
Having only 1/5 the number of nephrons likely results in a decline in kidney function due to the decreased number of functional units responsible for filtering blood and forming urine. This decrease in nephrons can lead to chronic kidney disease, not to an increase in kidney functions, more kidney infections, or kidney stones directly.
Step-by-step explanation:
If a grandma has only 1/5 the amount of nephrons, it is most likely that option C) Her kidney function declines due to decreased nephron number, is the correct answer. Nephrons are the functional units of the kidneys and are responsible for filtering blood and forming urine. When the number of functional nephrons declines, the glomerular filtration rate (GFR) also declines, leading to reduced kidney function. This is because nephrons play a critical role in maintaining fluid and electrolyte balance, and any significant loss in nephron number can lead to chronic kidney disease.
While the remaining nephrons may undergo compensatory hyperfiltration to maintain kidney function, this is not an increase in overall function but a response to reduce the workload. Over time, this can lead to further kidney damage. Therefore, having only 1/5 the amount of nephrons does not result in increased kidney function, make the individual more prone to kidney infections, or directly lead to the development of kidney stones as the other options suggested.