Which of the following statements is true for organisms classified in the kingdom Protista?

Introduction / Context:
Classification of living organisms into kingdoms and domains is a key topic in biology. The kingdom Protista contains a diverse group of organisms that do not fit neatly into the other kingdoms such as Plantae, Animalia, or Fungi. This question asks you to identify the statement that correctly describes a unifying feature of protists.

Given Data / Assumptions:
• Protists include algae, protozoa, and some slime molds. • They vary widely in lifestyle, nutrition, and form. • The question looks for a statement that is true for all members of the kingdom Protista.

Concept / Approach:
Modern classification divides life into three domains: Bacteria, Archaea, and Eukarya. Protists are part of domain Eukarya. This means that all protists have eukaryotic cells with a true nucleus and membrane bound organelles. However, they can be unicellular or multicellular, autotrophic or heterotrophic, and can live in many different environments. Therefore, you should look for a description that states they are eukaryotic but does not restrict them to a single mode of nutrition or number of cells.

Step-by-Step Solution:
Step 1: Recall that eukaryotic cells have a nucleus surrounded by a nuclear membrane and organelles such as mitochondria. Step 2: Remember that protists belong to the domain Eukarya, so they must be eukaryotic. Step 3: Think of examples like amoeba (heterotrophic, unicellular) and many algae (autotrophic, sometimes multicellular). These examples show that not all protists share the same nutrition or number of cells. Step 4: Evaluate each option and select the one that states a property shared by all protists without exceptions.

Verification / Alternative check:
Textbooks typically define protists as eukaryotic organisms that are not animals, plants, or fungi. This definition emphasizes their eukaryotic nature as the unifying feature. They can have great diversity in size and form. Checking this against the options, the only universally true statement is that all protists are eukaryotic and have membrane bound organelles.

Why Other Options Are Wrong:
Option A: Many protists are unicellular, but some algae and slime molds are multicellular or form large colonies, so this is not always true. Option B: Some protists are heterotrophic, but many algae are autotrophic and perform photosynthesis. Option C: This is also too narrow because not all protists are autotrophic; protozoa are typically heterotrophic. Option E: Prokaryotic cells lack a true nucleus and membrane bound organelles. Bacteria and archaea are prokaryotic, not protists.

Common Pitfalls:
Students often overgeneralize from a few examples. For instance, they may think all protists are unicellular because amoeba and paramecium are common textbook examples. Others may think all protists are plant like algae and therefore all autotrophic. To avoid these mistakes, remember that the key unifying feature is cell type rather than lifestyle. Protists are eukaryotic, meaning they have complex internal structure, but they show great diversity in every other respect.

Final Answer:
The correct statement is that all protists are eukaryotic and possess membrane bound organelles.