Assertion A flexeble wire loop of irregular shape carrying current when placed in a uniform external magnetic field acquires a circular shape.
Reason For a given perimeter circular shape is having the greatert area.

Answer

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

### Step 1: Understanding the Assertion
The assertion states that a flexible wire loop of irregular shape carrying current, when placed in a uniform external magnetic field, acquires a circular shape.

**Explanation**:
When a current-carrying conductor is placed in a magnetic field, it experiences a magnetic force. For a flexible wire loop, this force acts on each segment of the wire. The forces on the wire segments cause the loop to deform. The wire will tend to assume a shape that minimizes the energy and maximizes the magnetic flux through the loop.

### Step 2: Understanding the Reason
The reason states that for a given perimeter, a circular shape has the greatest area.

**Explanation**:
This is a well-known geometrical fact. Among all shapes with the same perimeter, the circle has the largest area. Therefore, if the wire loop is flexible and can change shape, it will naturally adjust to form a circle to maximize the area enclosed by the loop.

### Step 3: Connecting Assertion and Reason
The assertion can be explained by the reason. Since the flexible wire loop will adjust its shape to maximize the area, and since a circle provides the maximum area for a given perimeter, the wire loop will indeed take on a circular shape when placed in a uniform magnetic field.

### Conclusion
Both the assertion and the reason are true, and the reason correctly explains the assertion. Therefore, the answer to the question is:

**Assertion and Reason are both true, and the reason is the correct explanation for the assertion.**

### Final Answer
A: Assertion and Reason are both true, and the reason is the correct explanation for the assertion.

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