Protista differs from monera in having

A. Cell wall

B. Autotrophic nutrition

C. Flagella

D. Nuclear membrane

Bacteria belong to the kingdom Monera. They are prokaryotic, meaning they lack a true nucleus, though they do have a cell wall. Their genetic material is present as a circular DNA in the nucleoid region, without a nuclear membrane.

On the other hand, organisms in the kingdom Protista are unicellular and eukaryotic. Being eukaryotes, they possess a well-defined nucleus enclosed by a nuclear membrane, along with other membrane-bound organelles. Protists are more advanced than bacteria and are not classified as plants, animals, or fungi. They generally live in water or moist environments. Protists may be autotrophic, carrying out photosynthesis with the help of chloroplasts, or heterotrophic, depending on other organisms for food.

Additional Information:

• Fungi: Mostly filamentous (except yeast, which is unicellular), with thread-like structures called hyphae. A network of hyphae forms the mycelium.
• Plantae: Eukaryotic organisms with chloroplasts and cell walls made mainly of cellulose.
• Animalia: Multicellular eukaryotic heterotrophs without cell walls.

Hence, the correct answer is option D.