All the particles of a rigid rotating body move in a circular path when the axis of rotation:-

Options

A. passes through any point in the body
B. is situated outside the body
C. situated any where
D. passes through the centre of mass

Answer

To solve the question, we need to determine the conditions under which all particles of a rigid body rotating about an axis will move in a circular path. Let's analyze the options provided:

1. **Axis of rotation passes through any point in the body**:
- If the axis of rotation passes through a point in the body, that point will not move. Therefore, not all particles will be in circular motion since the point on the axis remains stationary.

2. **Axis of rotation is situated outside the body**:
- If the axis of rotation is outside the body, all particles of the rigid body can move in circular paths around that axis. This is because the distance from each particle to the axis remains constant, allowing for uniform circular motion.

3. **Axis of rotation is situated anywhere**:
- This is too vague. If the axis is within the body, as discussed in the first point, some particles will not move. Thus, this option cannot guarantee that all particles will move in circular paths.

4. **Axis of rotation passes through the center of mass**:
- Similar to the first option, if the axis passes through the center of mass, the center of mass itself will not move, and therefore, not all particles will perform circular motion.

From this analysis, we can conclude that the correct answer is:

**The axis of rotation is situated outside the body.**

### Step-by-Step Solution:

1. **Identify the problem**: We need to find the condition under which all particles of a rigid body move in a circular path during rotation.

2. **Analyze the first option**: If the axis of rotation passes through any point in the body, that point will remain stationary, and thus, not all particles will perform circular motion.

3. **Analyze the second option**: If the axis of rotation is outside the body, all particles can move in circular paths around that axis, as the distance from each particle to the axis remains constant.

4. **Analyze the third option**: The phrase "situated anywhere" is ambiguous. If the axis is within the body, some particles will not move, which means not all will be in circular motion.

5. **Analyze the fourth option**: If the axis of rotation passes through the center of mass, the center of mass will not move, leading to some particles not performing circular motion.

6. **Conclusion**: The only scenario where all particles of a rigid body will move in a circular path is when the axis of rotation is situated outside the body.

### Final Answer:
The axis of rotation is situated outside the body.