Answer :
The domain in which this organism is included is Eukarya. As the name indicates, Eukarya domain includes all the organisms which are made up of eukaryotic cells. Eukaryotic cells are kind of cells which have well defined nucleus and membrane bound organelles.
Further, this domain named Eukarya comprises 4 kingdoms which are mentioned as under:
1) Plantae
2) Animalia
3) Fungi
4) Protista
These 4 kingdoms include several organisms of varying characteristics but an organism having the mentioned characteristics i.e. multicellular, makes its own food, and is unable to move around its environment is specifically included in Kingdom Plantae.