Answer:
Option D, unicellular or multicellular, heterotrophic and lack cell walls.
Explanation:
Animal kingdom comprises of all organism that do not have cell wall which is a peculiar characteristic of plant kingdom. Also, unlike plants which are autotrophs (containing chlorophyll), animals are unable to make food of their own and hence are known as heterotrophs.
Animals can be multi-cellular (having multiple cells) like dog, cat etc and uni-cellular(having one cell only) like slipper animalcule.
Hence, option D is correct.
