The scientific method could not be used to study which of the following phenomena?

A. the authenticity of UFO sightings
B. the effects of second-hand smoke on household pets
C. the effect of daily exercise on gerbils
D. whether Vitamin C consumption reduces cold symptoms

A. the authenticity of UFO sightings

Explanation:

The Scientific Method refers to a procedure widely used in science that implies observation, measurement and a hypothesis that is formulated based on observations and then tested or proved through different methods. Because of this, phenomena that can be studied by using the scientific method are those that can be somehow controlled and tested and that are objective rather than subjective.

In the case of the phenomena "The authenticity of UFO sightings" this cannot be studied using the scientific methodology because this cannot be constantly observed, controlled or tested and also the "authenticity" is subjective rather than objective which makes almost impossible to observe the phenomena consistently, create a hypothesis and then prove it and therefore the Scientific Method cannot be applied to this phenomena.

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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.