What is skepticism? a new scientific ideabeing interested in new or different ideasa general agreement among scientists about a scientific ideathe understanding that knowledge in a particular area can be uncertain

i think the answer is b.

hope it

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.