Because the concordance rate for bipolar disorder among identical twins is biological causal explanations are

Bipolar disorder is a mood disorder characterized by alternating periods of mania mental illness marked by periods of great excitement, euphoria, delusions, and overactivity), and depression.

Concordance rates or the presence of bipolar disorder among identical twins is reported to be as high as 85%.  Biological causal explanations are: there is considerable overlap between the genes and imbalances in serotonin activity. Omega-3 fatty acids are reported to  provide protection from bipolar disorder

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.

a=c and then d= c because of the band so you get ac/dc and you add them together you get sound waves