Which of the following is not Darwin's conclusion?

Options

A. Survival of the fittest
B. Struggle for existence
C. Inheritance of acquired characters a
D. Origin of species by natural selection

Explanation

To solve the question "Which of the following is not Darwin's conclusion?", we will analyze the options provided in relation to Darwin's theory of evolution.

### Step-by-Step Solution:

1. **Understand Darwin's Theory**:
- Charles Darwin proposed the theory of natural selection, which explains how species evolve over time through a process of selection based on advantageous traits.

2. **Identify the Options**:
- The options given are:
a. Survival of the fittest
b. Struggle for existence
c. Inheritance of acquired characters
d. Origin of species by natural selection

3. **Analyze Each Option**:
- **Survival of the fittest**: This phrase summarizes Darwin's conclusion that individuals with advantageous traits are more likely to survive and reproduce. This is a key component of his theory.
- **Struggle for existence**: Darwin concluded that organisms compete for limited resources (food, water, habitat), leading to natural selection. This is also a fundamental aspect of his theory.
- **Inheritance of acquired characters**: This concept was proposed by Lamarck, not Darwin. Lamarck suggested that traits acquired during an organism's lifetime could be passed to offspring. This is not a conclusion drawn by Darwin.
- **Origin of species by natural selection**: This is the title of Darwin's famous book and encapsulates his theory. It is indeed one of his conclusions.

4. **Determine the Correct Answer**:
- Since "Inheritance of acquired characters" is associated with Lamarck and not Darwin, this option is the correct answer to the question.

### Final Answer:
The option that is not Darwin's conclusion is **c. Inheritance of acquired characters**.

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