The correct answer is 3. The organism is a prokaryote.
Step-by-step explanation:
Cells that are the basic unit for life are classified into eukaryotic or prokaryotic. In the case of prokaryotic cells, these differ from eukaryotic cells because they do not have a defined nucleus or bounded organelles; instead, ADN and similar are located in the cytoplasm.
Additionally, prokaryotic cells occur only in unicellular organisms such as bacteria or archaea, while other types of organisms such as plants, fungus or animals are composed of eukaryotic cells. This implies if the scientist discovered a microscope, unicellular organism with no nucleus, the organism is a prokaryote organism as this is these are the main features of prokaryotic cells or organisms.