Lactometers, as per BIS specifications are calibrated at | Agrigyan

• BIS Specifications for Lactometer Calibration:
• Bureau of Indian Standards (IS: 9585):
• Indian standard lactometers (such as Zeal and Quevenne types) are officially calibrated at $27^\circ\text{C}$ ($80.6^\circ\text{F}$), reflecting tropical ambient Indian dairy processing conditions.
• Temperature Correction Formula:

$$\text{CLR}_{\text{corrected}} = \text{CLR}_{\text{observed}} \pm 0.29 \times (T_{\text{observed}} - 27^\circ\text{C})$$

• Conclusion: 27°C (Option 1).

Correct option: (1) 27°C