Which of the following best describes a nuclear fusion reaction?
a reaction that forms chemical bonds
a reaction that breaks chemical bonds
a reaction that joins the nuclei of two atorns into one
a reaction that splits the nucleus of an atom into two
latinu
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A reaction that joins the nuclei of two atoms into one  

Explanation:

Think of the words "nuclear fusion".

Nuclear = "relating to a nucleus"

Fusion = "joining"

So, nuclear fusion is the joining of two nuclei into one.

A and B are wrong, because chemical reactions involve electrons.

D is wrong, because the splitting of a nucleus is fission.

Air enters through the nose (and sometimes the mouth), moves through the nasal cavity, the  pharynx, the  larynx, enters the  trachea, moves through the  bronchi  andbronchioles  till the alveoli.

The answer is lymph sinuses.