The correct answer is - Hot spot.
Kilaulea, as well as the Hawaiian-Emperor seamount chain are the result of a hot spot. Unlike most of the volcanoes on the planet that are located alongside the subduction zones on the plate boundaries, the Hawaiian volcanoes are far away from any plate border.
They are in fact in the middle of the Pacific plate, above a hot spot. The hot spot manages to penetrate through the crust of the plate, and creates a lot of volcanic activity. Over time, as the plate moves over the hot spot, some of the volcanoes that were active will stop with the volcanic activity because they will be dragged away from the hot spot, but others will emerge over the hot spot, thus creating a whole chain of volcanic islands.