Question

In which kingdoms are all organisms multicellular?

Answer 1

Multicellular organisms are reffered to as eukaryotes while unicellular organisms are reffered to as prokaryotes. Among the kingdoms, kingdom animalia and plantae are kingdoms in which microorganisms are considered as eukaryotes. 

Answer 2

Multicellular organisms are referred to as eukaryotes while the opposite, unicellular organisms, are called prokaryotes. Among all the kingdoms, I believe the kingdom which all organisms are multicellular are Animalia and Plantae. Hope this answers the question.