## Core Concept
To prepare normal saline from a given solution, one must understand the concept of osmolarity and the composition of the solutions involved. Normal saline is isotonic, having an osmolarity of approximately 300 mOsm/L, which is similar to that of human blood. Dextrose solutions are often used for their caloric content and to provide hydration.

## Why the Correct Answer is Right
The correct method to prepare normal saline from 10% dextrose involves understanding that 10% dextrose is hypertonic (approximately 1000 mOsm/L). To make it isotonic (like normal saline), one would need to dilute it. However, the exact preparation method isn't directly calculable without knowing the final volume and concentration desired. Typically, to make normal saline (0.9% NaCl solution), one would not start with dextrose but rather use sodium chloride. If the task involves diluting or adjusting dextrose to a saline solution, it seems there might be confusion in the question as dextrose and saline are usually separate solutions.

## Why Each Wrong Option is Incorrect
- **Option A:** Without specific details on the volumes or concentrations, it's hard to directly refute this option, but generally, preparing saline doesn't start with dextrose.
- **Option B:** Similarly, this option lacks context but mixing dextrose with saline isn't typically how saline is "prepared" from dextrose.
- **Option C:** This seems to imply a mixing or dilution process but is unclear without specifics.
- **Option D:** This option is marked as correct but without a clear method (e.g., dilution factor, volumes), it's hard to validate.

## Clinical Pearl / High-Yield Fact
A key point to remember is that normal saline (0.9% NaCl) is isotonic and used for hydration and as a vehicle for medications. Dextrose solutions are used for their caloric content. When preparing solutions for IV use, accuracy in concentration and volume is critical to avoid osmotic imbalances.

## Correct Answer: D.