Assertion (A): The net magnetic flux coming out of a closed surface is always zero.
Reason (R ): Unlike poles of equal strength exist together

Options

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

Explanation

To solve the given question, we need to analyze both the assertion and the reason provided.

### Step 1: Understand the Assertion
The assertion states that "The net magnetic flux coming out of a closed surface is always zero." This is based on Gauss's law for magnetism, which states that the total magnetic flux through a closed surface is zero. This is because magnetic field lines are continuous and do not begin or end at any point (there are no magnetic monopoles).

### Step 2: Understand the Reason
The reason given is "Unlike poles of equal strength exist together." This means that in any magnetic configuration, you will always have both a north and a south pole, and they exist in pairs. This reinforces the idea that magnetic field lines form closed loops, which contributes to the net magnetic flux being zero.

### Step 3: Analyze the Relationship
Now we need to determine if the reason correctly explains the assertion. Since the assertion is true (the net magnetic flux through a closed surface is zero), and the reason is also true (unlike poles exist together), we need to check if the reason provides a correct explanation for the assertion.

- The assertion is true because of the absence of magnetic monopoles.
- The reason is true as it describes the nature of magnetic poles.

### Step 4: Conclusion
Since both the assertion and the reason are true, and the reason provides a correct explanation for the assertion, we conclude that the correct option is:

**Option A: Both assertion and reason are true, and reason is the correct explanation of assertion.**