Answer :
Based on the theory of island biogeography, B. Kauai is expected to have the highest species richness among the Hawaiian islands.
The theory, developed by Robert H. MacArthur and Edward O. Wilson, posits that larger islands closer to a mainland generally have higher biodiversity due to easier access for species migration and larger available habitats.
Additionally, Kauai is the oldest of the Hawaiian islands, which means it has had more time for species to colonize and diversify.
Thus, option B is correct.