I'd go with the third one because the products of both of them are oxygen and carbon dioxide.
An insect bite on the face produces a break in the skin which introduces the normal skin flora (usually <em>Staphylococcus </em>and <em>Streptococcus</em>) to the sterile subcutaneous tissue causing inflammation. The inflammation of the subcutaneous tissue is called cellulitis. Since the infection is in the face, then it can travel from the infected site to the meninges through the cavernous sinuses and cause bacterial meningitis.
22. Species change over time
23. Observing
