• Determination of Milk Density via Pycnometer:
• Pycnometer (Specific Gravity Bottle):
• precision ground-glass flask with a capillary-bored stopper used to accurately determine the specific gravity and density of fluids.
• Working Principle:

• Standardized at a controlled temperature ($20^\circ\text{C}$ or $27^\circ\text{C}$), providing high accuracy in detecting watering or skimming adulteration (normal milk density: $1.028 - 1.034\text{ g/cm}^3$).
• Conclusion: Density (Option 1).

Correct option: (1) Density