Final answer:
The hygrometer reading shows a relative humidity of 65%, so the humidity level in the air is 65%.
Step-by-step explanation:
The question is asking to identify the relative humidity from a hygrometer reading. The hygrometer is showing a temperature of 30°C and a relative humidity of 65%. Thus, the humidity in the air is 65%. So the correct answer to the question is c) 65%.
In general, relative humidity is the amount of moisture in the air compared to what the air can hold at that temperature. If the temperature rises and the amount of moisture remains the same, the relative humidity will decrease because warm air can hold more moisture than cool air. If the temperature drops yet the moisture content stays the same, the relative humidity increases.