Assertion : All small oscillation are simple harmonic in nature.
Reason : Oscillation of spring block system are always simple harmonic whether amplitude is small or large.

Options

A. If both Assertion and Reason are true and the Reason is correct explanation of the Assertion.
B. If both Assertion and Reason are true but Reason is not the correct explanation of Assertion.
C. If Assertion is true, but the Reason is false.
D. If Assertion is false but the Reason is true.

Explanation

To solve the question regarding the assertion and reason statements, we will analyze both statements step by step.

### Step 1: Understand the Assertion
The assertion states: "All small oscillations are simple harmonic in nature."

- **Analysis**:
- Small oscillations can often be approximated as simple harmonic motion (SHM) under certain conditions, specifically when the restoring force is proportional to the displacement from the equilibrium position. However, not all small oscillations meet this criterion. For example, some systems may exhibit non-linear restoring forces even for small displacements, which would not classify them as SHM.

### Step 2: Understand the Reason
The reason states: "Oscillation of spring block system are always simple harmonic whether amplitude is small or large."

- **Analysis**:
- In a spring-block system, the restoring force is given by Hooke's Law, which states that the force is proportional to the negative displacement (F = -kx). This relationship holds true regardless of the amplitude of the oscillation, meaning that the motion will always be simple harmonic as long as the spring behaves linearly (which it typically does for small and moderate displacements).

### Step 3: Conclusion
Now, we can conclude the validity of both statements:

- The assertion is **incorrect** because not all small oscillations are simple harmonic; they must meet the specific condition of having a restoring force proportional to the displacement.
- The reason is **correct** because the oscillation of a spring-block system is indeed simple harmonic regardless of the amplitude, as long as the spring follows Hooke's Law.

### Final Answer
- The assertion is false, and the reason is true.