I'm pretty sure its c or d
Members of phylum Porifera are commonly known as spongs. They are generally marine and mostly asymmetrical animals. These are primitive multicellular animals and have cellular level of organization (lacks tissues). These Organisms (belonging to phylum Porifera) lacks most of the structures that are present in multicellular organisms like digestive system, respiratory system, Brain etc
Body of Spongs are made up of spicules or spongin fibers and these organism contain a water canal system which helps them in digestion, reproduction and catching their food in marine habitat.
Oxygen, nitrogen, carbon, hydrogen NOT magnesium
Answer - Fewer Species or Little of life
Reasoning - Usually in an island surrounded by water has little of life because the limited resources but also if there were to be species living within the island it will be very little because of the resources they compete. Especially moving away from mainland since (No Humans) lol.