I think C. You can't have just proteins or no fats in your diet. It needs to be balanced with a little of everything.
The nutrient that is not digested but keeps the digestive system healthy is C. Vitamins :)
it might cancel out large quantities of salt that are not needed
A. remove contaminants from people and equipment
decontamination: the process of cleaning an object or organism from contaminants and/or hazardous stuff/chemicals
I think superordinate is the few similarities among the others because it doesn’t sound right
