One of the revolutionary concepts in biology was Charles Drawin's Orgins of Species '. It delas with

Options

A. Gene
B. Use and disuse of organs
C. Germplasm theory
D. Natural selction leading to the survival of the fittest

Answer

### Step-by-Step Text Solution:

1. **Introduction to Darwin's Work**: Charles Darwin's "On the Origin of Species" is a foundational text in biology that introduced revolutionary concepts regarding the evolution of life.

2. **Focus of the Book**: The primary focus of this book is to explain the process of evolution through natural selection.

3. **Natural Selection Explained**: Natural selection is a mechanism by which individuals that are better adapted to their environment tend to survive and reproduce more successfully than others. This leads to the gradual evolution of species over time.

4. **Survival of the Fittest**: Darwin coined the phrase "survival of the fittest" to describe this process. It implies that those organisms that are most suited to their environment are more likely to survive and pass on their traits to the next generation.

5. **Opposition to Unfit Individuals**: Conversely, individuals that are less suited to their environment (the "unfit") are less likely to survive and reproduce, leading to a decrease in their representation in the population over time.

6. **Publication Details**: Darwin's "On the Origin of Species" was published in 1859, and it fundamentally changed the way we understand the development of life on Earth.

7. **Conclusion**: Therefore, the revolutionary concept in Darwin's work primarily deals with natural selection leading to the survival of the fittest.

### Final Answer:
The correct answer is option number 4: "natural selection leading to the survival of the fittest."

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