The observation of nucleus and other membrane-bound organelles provides evidence that a cell is most likely eukaryotic.
Step-by-step explanation:
The term eukaryotic refers to true nucleus or true kernel meaning that it has membrane-bound nucleus. Coiled structure of chromatin fibers can be seen in the eukaryotic nucleus.
This nucleus is bound by nuclear membrane, which can be seen attached or continuous with the stacked tube like structures of endoplasmic reticulum.
A double walled maze like Golgi bodies with ribosomes stacked to it and bean-shaped double walled mitochondria also can be uniquely observed in a eukaryotic cell .