## Core Concept
The reduced osmolarity Oral Rehydration Solution (ORS) is a type of solution used to treat dehydration caused by diarrhea. The World Health Organization (WHO) and UNICEF have recommended a reduced osmolarity ORS to prevent and treat dehydration in patients with diarrhea. The composition of this solution includes sodium chloride (NaCl), glucose, potassium chloride, and citrate.

## Why the Correct Answer is Right
The correct composition of reduced osmolarity ORS according to the WHO and UNICEF recommendations is 2.6 grams of sodium chloride (NaCl) per liter. This reduced osmolarity solution has been found to be more effective and safer than the original formula, reducing the osmolarity from 311 mOsm/L to 245 mOsm/L. The reduced osmolarity helps in better absorption of fluids and electrolytes by the intestine.

## Why Each Wrong Option is Incorrect
* **Option A:** This option suggests a higher amount of NaCl than recommended, which could potentially increase the osmolarity of the solution, making it less safe and effective.
* **Option B:** This option suggests a lower amount of NaCl, which might not provide sufficient sodium for absorption, potentially leading to hyponatremia or inadequate rehydration.
* **Option D:** This option suggests a completely different amount of NaCl, which does not align with the recommended composition of reduced osmolarity ORS.

## Clinical Pearl / High-Yield Fact
A key point to remember is that the reduced osmolarity ORS has a specific composition that has been widely adopted and recommended by global health authorities. The exact composition is: 2.6 grams of NaCl, 13.5 grams of glucose, 1.5 grams of potassium chloride, and 2.5 grams of trisodium citrate per liter of water. This solution is crucial in the management of diarrhea to prevent dehydration.

## Correct Answer Line
**Correct Answer: C. 2.6.**