Final answer:
Given its multicellularity and visible size, if the organism doesn't fit neatly into the kingdoms of plants, animals, or fungi, it is most likely a protist, which is a member of the Domain Eukarya and includes a wide variety of organisms.
Step-by-step explanation:
If an organism is multicellular and can be seen without a microscope, and it has a defined number of organelles within its cells, we are dealing with a eukaryotic organism because prokaryotic organisms generally do not have membrane-bound organelles. Organisms from the Domain Eukarya include those in the kingdoms of fungi, plants, animals, and protists. For this particular scenario, since the question implies that the organism is neither an animal, bacteria, plant, nor fungi but has eukaryotic characteristics, the likely classification would be a protist, a group within the Domain Eukarya that includes unicellular and multicellular organisms not fitting the strict definitions of the other eukaryotic kingdoms.
However, the information provided in the bar graph and the rest of the question details are essential to make an accurate assessment. If the organism has structures typical of plant cells (like chloroplasts), it might belong to Plantae. But without such data, and based on the general description given, the best fit would be Protista, as protists can be multicellular and visible without a microscope.