**Core Concept**
The question tests the understanding of **oral rehydration solutions**, specifically the **osmolarity of ReSoMal**, which is a type of oral rehydration solution used in the treatment of **severe malnutrition**. ReSoMal is designed to meet the unique needs of severely malnourished children.

**Why the Correct Answer is Right**
ReSoMal has a lower **osmolarity** compared to standard oral rehydration solutions, making it more suitable for children with severe malnutrition. This is because severely malnourished children are at risk of **osmotic imbalance** and require a solution that will not exacerbate this condition. The lower osmolarity of ReSoMal helps prevent **hypernatremia** and **hyperosmolarity**.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because it does not accurately reflect the osmolarity of ReSoMal.
**Option B:** This option is also incorrect as it represents the osmolarity of a different type of solution.
**Option D:** This option is incorrect because it is higher than the actual osmolarity of ReSoMal.

**Clinical Pearl / High-Yield Fact**
It's crucial to use ReSoMal in the treatment of severe malnutrition due to its appropriate **osmolarity** and **electrolyte composition**, which helps in the correction of **fluid and electrolyte imbalance**.

**Correct Answer:** C. 225 mOsm/L