Explanation:

- Here’s the thing about expert opinion under Section 45 of the Evidence Act:

- It’s considered when the court needs special knowledge, like in science or handwriting, to form an opinion.

- Option 1: Is a conclusive proof – This isn’t quite right. Even expert opinions can be questioned or contradicted; they’re not ‘final word’ proof.

- Option 2: Is not a conclusive proof –  This nails it. Courts look to expert opinions for help, but ultimately, judges decide the case, not the expert.

- Option 3: Is supportive & corroborative in nature – This is basically true too. Expert evidence supports the main case but doesn’t stand on its own.

- Option 4: Is not admissible – Totally off—the law specifically makes expert opinion admissible in relevant cases.