Final answer:
Approximately 6.7% of the total body water is found in the blood plasma, considering that extracellular fluids represent about 20% of the body weight and blood plasma makes up about 5% of that figure.
Step-by-step explanation:
The total body water is broadly composed of intracellular and extracellular fluids. The extracellular fluid represents about 20% of a human's body weight, with around 5% attributed to blood plasma. Given the options provided, the correct answer to the question 'How much of the total body water is generally found in the blood plasma?' is D. 6.7%. This is because if, for instance, an individual weighs 70 kilograms and approximately 60% of that weight is water (42 liters), the blood plasma would constitute 5% of the body weight (3.5 liters), which translates to approximately 6.7% of the total body water.