All of the following are drawbacks of Darwin's theory except

Options

A. This theory explains survival of the fittest but doesn't explain arrival of the fittest.
B. This theory does not explain the development of vestigial organs
C. This theory doesn't explain over - specialization of some organs like tusk of elephants
D. This theory doesn't explain the cause of struggle for existence.

Answer

To solve the question regarding the drawbacks of Darwin's theory, we need to analyze each option provided and determine which one is not a drawback according to Darwin's theory.

### Step 1: Understand the Drawbacks
1. **Survival of the fittest vs. arrival of the fittest**: This is a recognized drawback. Darwin's theory explains how the fittest survive but does not explain how they came to be fit in the first place.

2. **Development of vestigial organs**: This is also a recognized drawback. Darwin did not provide an explanation for the existence and evolution of vestigial organs, such as the appendix.

3. **Over-specialization in organisms**: This is another recognized drawback. Darwin's theory does not adequately explain why certain organisms, like elephants with tusks, have become over-specialized.

4. **Cause of struggle for existence**: This is where the misunderstanding lies. Darwin's theory does explain the struggle for existence and how organisms must compete to survive and reproduce.

### Step 2: Identify the Correct Answer
From the analysis above, the only statement that is not a drawback of Darwin's theory is the fourth one, which states that Darwin's theory does not explain the cause of struggle for existence. In fact, Darwin's theory does address this aspect.

### Conclusion
Thus, the correct answer to the question "All of the following are drawbacks of Darwin's theory except" is the fourth option.