Organisms which are multicellular eukaryotes without cell walls and are heterotroph are called ?

Option 1 -> Monera are prokaryotic organisms (like bacteria), not eukaryotes, and they possess cell walls.

Option 2 -> Protista are mostly unicellular eukaryotes, and many possess cell walls, not fitting the multicellular criterion.

Option 3 -> Plantae are multicellular eukaryotes but they have cell walls (cellulose) and are autotrophs, not heterotrophs.

Option 4 -> Animalia are multicellular eukaryotes that lack cell walls and obtain nutrition by consuming other organisms (heterotrophs).

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Hence, Option 4: Animalia -> These organisms possess all three defining characteristics: they are multicellular, eukaryotic, lack cell walls (allowing for greater flexibility and movement), and are heterotrophic (must consume organic material for energy) -> correct