Final answer:
The osmolality of plasma is approximately 285 to 295 mOsm/kg water, which is equivalent to about 0.3 Osm. This value indicates the plasma is isotonic, and its maintenance is crucial for appropriate hydration and bodily functions.
Step-by-step explanation:
The osmolality of plasma is a measure of the number of solutes in a solution, relative to the volume of solvent. In the context of blood plasma, this measure is critical as it is indicative of a person's hydration status. Among the options provided, the correct answer is B. 0.3 Osm. The normal osmolality of plasma, which is isotonic with respect to body fluids, is approximately 285 to 295 mOsm/kg water. This value, expressed in Osm, is closest to 0.3 Osm. The plasma osmolality is maintained within a narrow range by the body's regulatory mechanisms to ensure proper cellular function and overall health.