The correct answer is that the organism belongs to Phylum Phaeophyta (Brown Algae)
These multicellular organisms are called as brown algae and it contains fucoxanthin, beta carotene and chlorophyll c and no silica. They are known to be the most complex form of algae that are found in the marine environment.
They are autrophic muticellular organism and majority of them are found in the Northern Hemisphere but some of them also survive in the tropical warm water.