Which one of the following was not explained by Darwinism?

Options

A. Natural selection
B. Struggle for existence
C. Arrival of the fittest
D. Origin of species

Explanation

**Step-by-Step Solution:**

1. **Understanding Darwinism**: Darwinism primarily refers to Charles Darwin's theory of natural selection, which explains how species evolve over time through the process of adaptation to their environments.

2. **Key Concepts of Darwinism**:
- **Natural Selection**: The idea that organisms that are better adapted to their environment tend to survive and reproduce more than those that are less well adapted.
- **Struggle for Existence**: This concept involves competition among organisms for resources such as food, habitat, and mates, which is a fundamental aspect of Darwin's theory.
- **Origin of Species**: Darwin's work also discusses how new species arise through the process of evolution and adaptation.

3. **Identifying the Options**: The question asks which concept was not explained by Darwinism. The options typically include:
- Natural Selection
- Struggle for Existence
- Arrival of the Fittest
- Origin of Species

4. **Analyzing Each Option**:
- **Natural Selection**: Explained by Darwin as a mechanism of evolution.
- **Struggle for Existence**: Also explained by Darwin, referring to the competition for survival.
- **Origin of Species**: Discussed in Darwin's work, particularly in his book "On the Origin of Species".
- **Arrival of the Fittest**: This phrase was actually coined by Herbert Spencer, not Darwin. Therefore, it is not part of Darwin's explanations.

5. **Conclusion**: The concept that was not explained by Darwinism is the "Arrival of the Fittest".

**Final Answer**: Arrival of the Fittest (coined by Herbert Spencer).

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