Read this sentence from the main text:

Furthermore, mucus is not just the nasty gunk you see when you are sick.
What purpose does this sentence serve in the text as a whole?

#1 It connects the previous supporting detail to a new point.
#2 It connects a new point to the final paragraph.
#3 It connects the paragraph to the text about names.
#4 It suggests there is one final point to discuss regarding mucus.