## Core Concept
The human body is primarily composed of water, which makes up approximately 60% of an adult's body weight. This water is distributed into two main compartments: intracellular fluid (ICF) and extracellular fluid (ECF). The balance and distribution of body water are crucial for maintaining proper bodily functions.

## Why the Correct Answer is Right
The correct answer, , states that about 2/3 of the body water is intracellular and 1/3 is extracellular. This distribution is accurate because the intracellular compartment contains approximately 40 liters of water (about 2/3 of total body water) and the extracellular compartment contains about 20 liters (about 1/3 of total body water) in an average adult. This distribution is maintained by various factors including osmotic pressures, membrane permeability, and active transport mechanisms.

## Why Each Wrong Option is Incorrect
* **Option A:** This option is incorrect because it inaccurately represents the distribution of body water. Without specific details on the percentages or ratios provided in the option, we can infer that any option not stating the 2/3 intracellular and 1/3 extracellular distribution is incorrect.
* **Option B:** Similarly, this option is incorrect for not accurately reflecting the known distribution of body water between intracellular and extracellular compartments.
* **Option D:** This option is also incorrect as it does not correctly represent the proportion of body water in each compartment.

## Clinical Pearl / High-Yield Fact
A key point to remember is that the distribution of body water can change due to various clinical conditions such as dehydration, overhydration, or electrolyte imbalances. Understanding the normal distribution and its regulation is crucial for managing fluid and electrolyte therapy in patients.

## Correct Answer: C.