When you destroy a part of the brain to see what function that area had, what method is this?.

explanation:

b,bacteria convert nitrates

into nitrogen gas.

d,plants and animals take in

and use nitrogen compounds.

e,bacteria break down waste    

products and return nitrogen  

to the soil.

a,bacteria convert atmospheric

nitrogen to ammonia.

c,bacteria convert ammonia

to nitrites and nitrates.

this is more of a statement than a question. is there answers to go along with this, or is it opinion based?

i think the answer is a.keratin is the pigment responsible for skin color.