The total number of species, that are known and described , range between:

Options

A. `0 . 5 - 1 . 0` million
B. `1.1-1.2` million
C. `1.7-1.8` million
D. `2.5-3.0` million

Answer

To answer the question regarding the total number of known and described species, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Biodiversity**:
- Biodiversity refers to the variety of life on Earth, encompassing all species of plants, animals, fungi, and microorganisms.

2. **Known Species**:
- Scientists have been documenting and describing species for centuries. However, it is important to note that not all species have been discovered or described yet.

3. **Estimation of Total Species**:
- Current estimates suggest that the total number of species on Earth ranges between 1.7 billion to 1.8 billion. This includes all known and described species across various taxa.

4. **Continuous Discovery**:
- New species are continually being discovered, especially in biodiverse regions like the Amazon rainforest, where many areas remain unexplored. This means that the number of known species is constantly changing as new discoveries are made.

5. **Conclusion**:
- Therefore, the total number of species that are known and described ranges between 1.7 billion to 1.8 billion.

### Final Answer:
The total number of species that are known and described ranges between **1.7 billion to 1.8 billion**.

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