## **Core Concept**
The World Health Organization's Oral Rehydration Solution (WHO ORS) is a type of fluid replacement used to prevent and treat dehydration, especially due to diarrhea. It contains specific amounts of salts and sugars to help the body absorb fluids. The composition is designed to facilitate the absorption of sodium and water by the intestines.

## **Why the Correct Answer is Right**
The correct composition of the WHO ORS includes sodium chloride (NaCl), glucose (anhydrous), potassium chloride (KCl), and trisodium citrate (or sodium citrate). The reduced osmolarity ORS, which is the current formulation, contains:
- Sodium chloride (NaCl) - 2.6 grams/L
- Glucose, anhydrous - 13.5 grams/L
- Potassium chloride (KCl) - 1.5 grams/L
- Trisodium citrate dihydrate - 2.9 grams/L

This composition helps in the cotransport of sodium and glucose across the intestinal mucosa, facilitating water absorption.

## **Why Each Wrong Option is Incorrect**
- **Option A:** This option is incomplete as it does not specify all the components of the WHO ORS.
- **Option B:** Similarly, this option lacks completeness regarding the components of the WHO ORS.
- **Option D:** This option might include incorrect or incomplete information regarding the composition of WHO ORS.

## **Clinical Pearl / High-Yield Fact**
A key point to remember is that the WHO ORS has evolved, and the current reduced osmolarity formula has been shown to be more effective and safer than the original formula, with less stool output and fewer vomiting episodes. The composition is crucial for its effectiveness in treating dehydration.

## **Correct Answer:** .