How does the biological species concept identify two different species?
a. reproductive isolation
b. asexual reproduction
c. interaction between two species

The biological species concept identify two different species by reproductive isolation.  

Explanation:

In biological Species theory if organisms can interbreed and produce healthy and fertile offspring they belong to same specie. Speciation is the process of emergence of new specie from the existing population. When a group of organisms within a specie become reproductively isolated it give rise to the new specie.

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when you breathe in, or inhale, your diaphragm contracts (tightens) and moves downward. this increases the space in your chest cavity, into which your lungs expand. the intercostal muscles between your ribs also enlarge the chest cavity. they contract to pull your rib cage both upward and outward when you inhale.