The present mass extinction

Options

A. `3^(rd)`
B. `4^(th)`
C. `5^(th)`
D. `6^(th)`

Answer

### Step-by-Step Solution:

1. **Understanding Mass Extinction**: A mass extinction event is characterized by a significant and rapid decrease in the biodiversity on Earth. Historically, there have been five major mass extinctions, and scientists are now suggesting that we are experiencing a sixth.

2. **Historical Context**: The five previous mass extinctions occurred over millions of years and were caused by natural events such as volcanic eruptions, climate change, and asteroid impacts. The current situation is different because it is largely driven by human activities.

3. **Current Extinction Rates**: Between 1900 and 2015, studies have shown that nearly half of the surveyed mammal species have lost more than 80% of their distribution. This indicates a severe decline in populations of various species, including mammals, birds, reptiles, and amphibians.

4. **Human Impact**: The rapid increase in human population and the overuse of natural resources are significant factors contributing to this current extinction crisis. Habitat destruction, pollution, climate change, and overexploitation of species are all consequences of human activity that are accelerating extinction rates.

5. **Current Extinction Classification**: Scientists estimate that the current rates of species extinction are 100 to 1000 times faster than the natural background extinction rates observed before human influence. This alarming rate has led to the classification of the ongoing extinction event as the sixth mass extinction, also referred to as the Anthropocene extinction.

6. **Conclusion**: Based on the evidence and the factors contributing to the current biodiversity crisis, the present mass extinction is classified as the sixth mass extinction.

### Final Answer:
The present mass extinction is the **6th mass extinction**.

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