Final answer:
Protists and fungi are placed in the same domain, Eukarya, because they both have membrane-enclosed nuclei.
(Option B)
Step-by-step explanation:
Protists and fungi are placed in the same domain, Eukarya, because they both have membrane-enclosed nuclei. Unlike prokaryotic cells found in bacteria and archaea, both protists and fungi have eukaryotic cells that contain a nucleus and membrane-bound organelles. Although they have similar physical features like cell walls and spore reproduction, the main reason they are placed in the same domain is because of their shared eukaryotic cell structure.
Furthermore, the presence of complex cellular structures such as the endoplasmic reticulum, Golgi apparatus, and mitochondria in both protists and fungi aligns them within the Eukarya domain, emphasizing their shared evolutionary ancestry and cellular complexity.