Air can be disinfected using
a. hepa fiters
b. ethylene oxide
c. uv light
d. a& c
e. b& c

C. UV light  

Explanation:

Some air purifiers use catalyzed ultraviolet light to disinfect the air. In oxidative processes with ultraviolet radiation (UV), high quality UV lamps, yield and radiation react with titanium that catalyzes the "burning" of microorganisms, odors and impurities difficult control by the usual systems.

Ultraviolet light eliminates the formation of mold in the air conditioning system, reduces the incidence of viruses and bacteria, preventing their multiplication and disinfects air that passes through the air conditioning system.

i am going to guess that it is co2.

clumped distribution, because you'de have all of the population gathered in a relatively small are.

it's the most common because it provides protection and a mate for reproduction

example: humans, seeweed, cattles, etc.