## **Core Concept**
The body loses water through various routes, one of which is the skin. Even in the absence of sweating, the skin continues to lose water through a process known as **insensible water loss**. This occurs due to the diffusion of water through the skin.

## **Why the Correct Answer is Right**
The correct answer, **. 300-400 mL**, represents the daily loss of water from the skin in the absence of sweating. This amount is a result of the insensible water loss, which is an unavoidable loss of water through the skin and respiratory tract. The skin's permeability and the gradient of water concentration across the skin contribute to this loss. This process is essential for maintaining skin hydration but also needs to be considered in the overall fluid balance of the body.

## **Why Each Wrong Option is Incorrect**
- **Option A:** . 100-200 mL - This is lower than the generally accepted range for insensible water loss through the skin. While there is some variability, 100-200 mL is on the lower side and does not accurately reflect the typical daily loss.
- **Option B:** . 500-600 mL - This option suggests a higher rate of water loss than what is typically considered for insensible loss through the skin alone. It might be more reflective of total insensible loss (including respiratory tract).
- **Option D:** . 700-800 mL - This is significantly higher than the usual estimate for daily insensible water loss through the skin and might overestimate the amount.

## **Clinical Pearl / High-Yield Fact**
A key point to remember is that the total insensible water loss (from skin and respiratory tract) is approximately **800-1000 mL/day**. Of this, about **300-400 mL** is lost through the skin in the absence of sweating. Understanding this helps in managing fluid balance, especially in critically ill patients or those with significant fluid disturbances.

## **Correct Answer:** . 300-400 mL.