Question

the instrument that measures wet-bulb and dry-bulb temperatures is the
anemometer.
refractometer.
psychrometer.
velometer.

Explanation:

• An anemometer measures wind speed, not wet - bulb and dry - bulb temperatures.
• A refractometer is used to measure the refractive index of a substance, often for determining the concentration of a solution, not related to temperature measurement.
• A psychrometer is specifically designed to measure wet - bulb and dry - bulb temperatures, which are used to calculate humidity.
• A velometer is used to measure velocity (usually of air or other fluids), not temperatures.

Answer:

C. psychrometer