What Happened to Make the Shrimp Living Around the Border

What happened to make the shrimp living around the border of the Americas diverge into twice as many species as there were originally?

A) The Panama canal allowed them to move into the same environment, and competition led to speciation.
B) The Panama Isthmus sank below sea level, allowing the Pacific and Caribbean oceans to mix, and the shrimp mixed too, resulting in speciation.
C) The Pacific ocean and Caribbean sea changed with the climate, and this selected for a wider variety of shrimp species.
D) Nobody knows how this happened, they only know that the shrimp are closely related to each other.
E) The Panama Isthmus rose above sea level, separating the Pacific and Caribbean oceans and isolating shrimp in both oceans, where they evolved separately and speciated.