Unicellular eukaryotic organisms are included in

Options

A. Monera
B. Protista
C. Fungi
D. Plantae

Explanation

**Step-by-Step Solution:**

1. **Understanding the Question**: The question asks about the classification of unicellular eukaryotic organisms. We need to identify which kingdom they belong to among the options provided: Monera, Protista, Fungi, and Plantae.

2. **Reviewing the Five Kingdoms**: According to R.H. Whittaker's five-kingdom classification, the kingdoms are:
- Monera: Contains prokaryotic organisms (e.g., bacteria).
- Protista: Contains unicellular eukaryotic organisms.
- Fungi: Mostly multicellular eukaryotic organisms.
- Plantae: Multicellular eukaryotic organisms that are primarily photosynthetic.
- Animalia: Multicellular eukaryotic organisms that are heterotrophic.

3. **Identifying Unicellular Eukaryotes**: Unicellular eukaryotic organisms are those that consist of a single cell and have a defined nucleus. The key point is that they are eukaryotic, which means they belong to a group that has complex cells.

4. **Analyzing the Options**:
- **Monera**: This kingdom includes prokaryotic organisms, which do not have a nucleus, so this option is incorrect.
- **Protista**: This kingdom is specifically known for containing unicellular eukaryotic organisms, making this option a strong candidate.
- **Fungi**: While fungi are eukaryotic, they are primarily multicellular, so this option is incorrect for unicellular organisms.
- **Plantae**: This kingdom consists of multicellular organisms, primarily photosynthetic, so this option is also incorrect.

5. **Conclusion**: Based on the classification and the characteristics of the kingdoms, unicellular eukaryotic organisms are included in the **Protista** kingdom.

**Final Answer**: Unicellular eukaryotic organisms are included in the **Protista** kingdom.

---