In the Oceans on Either Side of the Isthmus of Panama

In the oceans on either side of the Isthmus of Panama are 30 species of snapping shrimp; some are shallow-water species, others are adapted to deep water. There are 15 species on the Pacific side and 15 different species on the Atlantic side. The Isthmus of Panama started rising about 10 million years ago. The oceans were completely separated by the isthmus about 3 million years ago.
In the figure, the isthmus separates the Pacific Ocean on the left (side A) from the Atlantic Ocean on the right (side B) . The seawater on either side of the isthmus is separated into five depth habitats (1-5) , with 1 being the shallowest.

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Which habitats should harbour snapping shrimp species with the greatest degree of genetic divergence from each other?
Divergence from each other?

A) A1 and A5
B) A1 and B5
C) A5 and B5
D) Both A1/A5 and B1/B5 should have the greatest, but equal amounts of, genetic divergence