Answer :
The acceptable temperature range for coffee before putting it into the digital refractometer is 150-160 degrees Fahrenheit and hence the correct option is c. 150-160 degrees Fahrenheit.
To measure the concentration of coffee using a digital refractometer, the temperature of the coffee is an essential factor to get accurate results. Most handheld coffee refractometers are calibrated for use at a temperature range from 60-80 0C (140-176 0F).
Therefore, the correct answer is 150-160 degrees Fahrenheit, which is within this acceptable range for the refractometer's calibration. It's important to ensure the coffee has cooled adequately and falls within this range before measurement to avoid damage to the refractometer and to ensure precision.
