All eukaryotic unicellular organisms belong to (A) Monera(B) Protista(C) Fungi(D) Bacteria

The correct answer is (B) Protista.

Explanation: Eukaryotic unicellular organisms are those that have a defined nucleus and organelles within their cells. These organisms are typically classified under the kingdom Protista.

The kingdoms are classified as follows:

Monera: Includes prokaryotic organisms, such as bacteria and archaea. These organisms do not have a defined nucleus.
Protista: This kingdom includes eukaryotic organisms that are unicellular or multicellular but do not form true tissues. Examples include amoeba, paramecia, and certain algae.
Fungi: This kingdom includes multicellular eukaryotic organisms such as mushrooms, molds, and yeasts. Most fungi are not unicellular (except for some like yeasts).
Bacteria: Bacteria are prokaryotic organisms, so they are not eukaryotic.
Thus, eukaryotic unicellular organisms belong to the kingdom Protista.