Protista differs from monera in having
A. Cell wall
B. Autotrophic nutrition
C. Flagella
D. Nuclear membrane

Hint: Whittaker proposed an elaborate five-kingdom classification-Monera, Protista, Fungi, Plantae and Animalia. This classification was based upon certain characters like mode of nutrition, thallus organisation, cell structure, phylogenetic relationships and reproduction.

Complete answer: Bacteria are categorized under the kingdom monera. They possess a cell wall and are prokaryotic in nature, whereas kingdom Protista includes unicellular and eukaryotic organisms. Being eukaryotes, it contains a well-defined nucleus and other membrane-bound organelles. Monerans do not possess a true nucleus, whereas Protista has its own nuclei bound with the nuclear membrane.
Protists are much more advanced than bacteria. They are neither plants nor animals or fungi. Organisms that belong to protists live in water, moist places, etc. They may be autotrophic or heterotrophic in nature. Autotrophic protists have cell organelles that help them to undergo photosynthesis, while heterotrophic protists depend on other organisms for nutrition. Bacteria contain genetic material in the form of a circular DNA that is suspended in the nucleoid since they do not have a double membrane nuclear envelope.

Additional information: Along with Monera and Protista, there are other kingdoms like Fungi, Plantae and Animalia. The fungi are filamentous including yeast (single-celled). They have a long thread like structures called hyphae. The web of hyphae is called mycelium. The kingdom Plantae consists of eukaryotes that have chloroplasts and their cell wall mainly comprises cellulose. All multicellular eukaryotes which are heterotrophs are included under this kingdom of Animalia.
Hence, the correct answer is option D.

Note: Prokaryotic cells differ from eukaryotic cells in various aspects; for example, most of the cell organelles are absent in prokaryotes. They also differ in size; prokaryotic cells are smaller as compared to eukaryotic cells.