which of the following must occur for speciation to happen?\no geographic isolation\no reproductive…

Brief Explanations:

Speciation is the formation of new species. Reproductive isolation is the key factor that must occur for speciation. It prevents gene - flow between populations, leading to genetic divergence and the formation of new species. Geographic isolation can lead to speciation but is not always necessary. Temporal and behavioral isolations are types of pre - zygotic reproductive isolations, but the overarching concept of reproductive isolation is what is essential for speciation to happen.

Answer:

reproductive isolation