Question

in the definition of the biological species concept, what is the most important concept in the definition of species?
ecological distinctions
differences in dna
reproductive isolation
differences in morphology

Explanation:

The Biological Species Concept defines a species as a group of organisms that can interbreed and produce fertile offspring, and are reproductively isolated from other such groups. Reproductive isolation is the key concept that differentiates one species from another under this concept. Ecological distinctions, DNA - differences, and morphological differences can be used in other species - concepts but are not the core of the Biological Species Concept.

Answer:

C. reproductive isolation