Intracellular fluid (2/3 of body water) is fluid contained within cells. In a 72-kg body containing 40 litres of fluid, about 25 litres is intracellular, which amounts to 62.5%. Jackson's texts states 70% of body fluid is intracellular.

The intracellular fluid compartment contains the fluid that is present in the cytoplasm of all cells of the body. This compartment holds approximately 67% of the total volume of body fluids. Therefore, option 'A' is the correct answer.

The answer is option 'A' which is intracellular fluid.

Explanation:

Our body is composed of about 60% water, which is distributed in various fluid compartments. The two major fluid compartments are intracellular fluid and extracellular fluid.

Intracellular fluid:
- It refers to the fluid within the cells, which is surrounded by the cell membrane.
- It contains about 67% (by volume) of all body water.
- Its composition is different from extracellular fluid because it contains high levels of potassium and magnesium ions, as well as proteins and other molecules that are specific to the cell's function.

Extracellular fluid:
- It refers to the fluid outside the cells, which includes interstitial fluid (between the cells) and plasma (the liquid component of blood).
- It contains about 33% (by volume) of all body water.
- Its composition is different from intracellular fluid because it contains high levels of sodium and chloride ions, as well as other molecules that are important for maintaining the body's pH, osmotic balance, and other physiological functions.

Lymph:
- It is a clear liquid that circulates in the lymphatic system.
- It is a part of extracellular fluid and is derived from interstitial fluid.
- It contains white blood cells and other immune cells that are important for fighting infections.

In conclusion, the intracellular fluid compartment contains the majority of body water (about 67% by volume), while the extracellular fluid compartment and lymph contain the remaining water.