Which is the most commonly used classification scheme?

Options

A. Linnaeus's five kingdom scheme
B. Whittaker's five kingdom scheme
C. Darwin's five kingdom scheme
D. Hooke's five kingdom scheme

Explanation

### Step-by-Step Solution:

1. **Understanding Classification Schemes**:
- Classification schemes are methods used to categorize living organisms based on various characteristics.

2. **Identifying the Options**:
- The options provided are:
- Linnaeus' 5 kingdom scheme
- Whittaker's 5 kingdom scheme
- Darwin's 5 kingdom scheme
- Hooke's 5 kingdom scheme

3. **Recognizing the Most Commonly Used Scheme**:
- The most commonly used classification scheme is Whittaker's 5 kingdom scheme, proposed by R.H. Whittaker in 1969.

4. **Understanding Whittaker's 5 Kingdoms**:
- Whittaker classified living organisms into five kingdoms:
1. **Monera**: Single-celled prokaryotes (e.g., bacteria).
2. **Protista**: Single-celled eukaryotes (e.g., amoeba, paramecium).
3. **Fungi**: Organisms that absorb nutrients (e.g., mushrooms, yeast).
4. **Plantae**: Photosynthetic organisms (e.g., plants).
5. **Animalia**: Multicellular organisms that are heterotrophic (e.g., animals).

5. **Criteria for Classification**:
- Whittaker's classification is based on several criteria:
- **Cell Structure**: Prokaryotic vs. eukaryotic.
- **Body Organization**: Unicellular vs. multicellular.
- **Presence of Cell Wall**: Whether the organism has a cell wall or not.
- **Mode of Nutrition**: Autotrophic (self-feeding) vs. heterotrophic (feeding on others).
- **Mode of Reproduction**: Sexual vs. asexual reproduction.
- **Phylogenetic Relationships**: Evolutionary relationships among organisms.

6. **Conclusion**:
- Therefore, the answer to the question is Whittaker's 5 kingdom scheme, which is the most commonly used classification system.