This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Air, Light, Sound, Housing, Radiation, Waste Disposal, Subject name: Social & Preventive Medicine
Psychrometer is used to measure: 
Select and explain. 
A. Humidity, B. Air velocity, C. Air temperature, D. Radiant heat
A: Humidity
Answer: A: Humidity 
Explanation: AIR HUMIDITY Air humidity is moisture content of air Air humidity can be measured by: Dry and wet bulb thermometer Hygrometer- most widely used. Sling/ whirling psychrometer Assman psychrometer Assman psychrometer Air temperature: Six's maximum-minimum thermometer measures maximum & minimum air temperatures reached over a period of time.