In Whittaker's classification Archaebacteria and nitrogen fixing algae are placed under

Options

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

Answer

To solve the question regarding the classification of Archaebacteria and nitrogen-fixing algae in Whittaker's classification, we can follow these steps:

### Step-by-Step Solution:

1. **Understand Whittaker's Classification**: R.H. Whittaker proposed a five-kingdom classification system that includes Monera, Protista, Fungi, Plantae, and Animalia.

2. **Identify the Characteristics of the Kingdoms**:
- **Monera**: This kingdom includes prokaryotic organisms, which are unicellular and lack a well-defined nucleus and organelles. It encompasses bacteria, including Archaebacteria and nitrogen-fixing bacteria.
- **Protista**: This kingdom consists of mostly unicellular eukaryotic organisms.
- **Fungi**: This kingdom includes multicellular eukaryotic organisms that are heterotrophic.
- **Plantae**: This kingdom includes multicellular eukaryotic organisms that are autotrophic.
- **Animalia**: This kingdom includes multicellular eukaryotic organisms that are also heterotrophic.

3. **Classify Archaebacteria and Nitrogen-Fixing Algae**:
- **Archaebacteria**: These are prokaryotic organisms that belong to the kingdom Monera.
- **Nitrogen-Fixing Algae**: Although they are often referred to as algae, nitrogen-fixing algae (like cyanobacteria) are also prokaryotic and fall under the kingdom Monera.

4. **Choose the Correct Option**: Based on the classification, both Archaebacteria and nitrogen-fixing algae are placed under the kingdom Monera.

5. **Final Answer**: The correct answer is **Option C: Monera**.