The two key concepts of Darwinian theory of evolution are

Options

A. Fitness
B. Branching descent
C. Natural selection
D. Both 2 and 3

Answer

To answer the question regarding the two key concepts of Darwinian theory of evolution, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Darwin's Theory**: The theory of evolution proposed by Charles Darwin is primarily encapsulated in his book "On the Origin of Species." It lays the foundation for our understanding of how species evolve over time.

2. **Identifying Key Concepts**: The two fundamental concepts of Darwinian evolution are:
- **Natural Selection**: This concept explains how certain traits become more common in a population because they provide some advantage in survival and reproduction. Organisms that are better adapted to their environment tend to survive and produce more offspring.
- **Branching Descent**: This concept refers to the idea that all species are linked through a common ancestor and that species diverge over time through a process of branching evolution. This explains the diversity of life on Earth.

3. **Evaluating Options**: The options provided are:
- A) Fitness
- B) Branching descent
- C) Natural selection
- D) Both B and C

Based on our understanding, both "Branching descent" and "Natural selection" are key concepts of Darwin's theory.

4. **Conclusion**: Therefore, the correct answer is option D, which states that both branching descent and natural selection are the two key concepts of Darwinian theory of evolution.

### Final Answer:
The two key concepts of Darwinian theory of evolution are **Branching Descent** and **Natural Selection** (Option D).

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