Final answer:
The multicellular, heterotrophic, eukaryotic organism from the pond belongs to the domain Eukarya, which includes organisms with cells that have a nucleus.
Step-by-step explanation:
An organism collected from a pond that is multicellular, heterotrophic, and eukaryotic belongs in the domain Eukarya. This domain is characterized by organisms that have cells with a nucleus and includes kingdoms such as fungi, plants, animals, and protists. In contrast, the domains Archaea and Bacteria consist of prokaryotic organisms, which lack a nucleus and other membrane-bound organelles. Since the organism in question is eukaryotic, it does not belong to the prokaryotic domains of Archaea or Bacteria.