Mutagens are useful in biotechnology research for producing organisms with altered phenotypes. producing new organisms which have beneficial traits from two or more organisms. selecting genetic mutants resistant to radioactivity. removing undesirable traits from microbes. producing DNA fragments for cloning.

The correct answer is A.

Explanation:

A mutagen changes the level of mutations that occur in the DNA either by affecting it physically or chemically. This helps researchers create different organisms with altered phenotypes according to what the research needs so that the genes can be investigated further under a controlled environment.

So the answer is A.

I hope this helps.

the correct answer is - ability to find a mate

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.