A motile prokaryotic organism was found in the hot thermal geysers of Iceland. In which kingdom would this organism be found?

Archaea

Explanation:

The kingdom Archaebacteria includes prokaryotic microbes with some unique features to enable them to survive in most hostile conditions. These microbes are found under the conditions of the extremely high temperature such as that of hot thermal geysers of Iceland.

The Archaebacteria found in these habitats are called thermophilic archaeans as they are able to survive the extremely high temperatures.