What Is the Correct Order of the Steps Regarding Speciation $\rightarrow$

What is the correct order of the steps regarding speciation?

A) geographic isolation $\rightarrow$ one species $\rightarrow$ reproductive isolation $\rightarrow$ two species
B) two species $\rightarrow$ geographic isolation $\rightarrow$ one species $\rightarrow$ reproductive isolation
C) one species $\rightarrow$ geographic isolation $\rightarrow$ reproductive isolation $\rightarrow$ two species
D) reproductive isolation $\rightarrow$ one species $\rightarrow$ reproductive isolation $\rightarrow$ two species
E) reproductive isolation $\rightarrow$ two species $\rightarrow$ reproductive isolation $\rightarrow$ one species