They would have to look at the root of the hair.
Answer:
Nitrogen is present in the atmosphere in a molecule form about 78 percent. This nitrogen comes to the earth with the water through rainfall. Some nitrogen fix by beneficial microorganisms such as Cyanobacteria and Azotobactor which are present in the roots of higher plants. These microorganisms convert nitrogen molecule into nitrates and used by the plants. There are some other microorganisms which again convert nitrate into nitrogen molecules, called denitrifying bacteria and nitrogen molecule goes to the atmosphere again and complete the cycle.
The model attached represents facilitated transport, which is answer choice D. In the model, there are protein channels, which allow molecules to pass through them if they're too large to fit through the aquaporins (making diffusion an incorrect answer.) We can eliminate active transport since ATP isn't used to control transport, and we can eliminate endocytosis as it is a form of active transport. The remaining answer would be facilitated transport, which is a form of passive transport. Hope this helps! :)