Joan completed a science experiment using a sling psychrometer. She made the following notes in her science journal. Joan made one mistake while recording her notes. Which sentence reveals her mistake?

Below are the choices:

It felt hot in the science lab, and my skin felt sticky. I ran the experiment by spinning the sling psychrometer. There was a very small difference in the dry bulb and wet bulb temperatures. This is the result of the water on the wick of the wet bulb evaporating rapidly. The evaporation caused a slight drop in the level of mercury in the wet bulb. I conclude that the relative humidity in the lab is very high.

I think the answer should be The evaporation caused a slight drop in the level of mercury in the wet bulb.