Choice A reason:

Dark urine and pale-colored stools are not typically associated with a gastrointestinal infection. These symptoms are more indicative of changes in bile flow or bilirubin excretion.

Choice B reason:

While cholecystitis can lead to malabsorption of nutrients, it is not the primary cause of changes in stool color to pale.

Choice C reason:

This statement is correct. Cholecystitis can obstruct the bile duct, leading to a decrease in bilirubin excretion. Bilirubin gives urine its characteristic color, and when excretion is reduced, the urine becomes darker (brownish). Likewise, the absence of bilirubin in the stool leads to pale-colored or clay-colored stools.

Choice D reason:

Dehydration may occur in some cases of cholecystitis, but it is not the primary cause of changes in urine and stool color.