Explanation:

This question presents a scenario where the cause of an obstruction in a harbour is in question, and then provides a related fact: other similar harbours without sea walls also experienced obstruction at the same time. It asks under which section of the Indian Evidence Act, 1872, this related fact would be relevant. Let's analyze the nature of the question and the provided options: The core question is about causation: whether a specific sea wall caused an obstruction. This is a matter that often requires specialized knowledge or expert opinion (e.g., in marine engineering, hydrology, or coastal dynamics). The fact provided is an 'analogous fact' or a 'similar fact' – other similar harbours, *without* the specific sea wall, experienced the *same problem* at the *same time*. This fact tends to negate the causal link between the sea wall and the obstruction in the first harbour, or at least suggests an alternative common cause. Now, let's look at the sections of the Indian Evidence Act provided as options, which primarily deal with opinions of experts: Option (1): "Section 45A". Section 45A deals with the opinion of the Examiner of Electronic Evidence. This is a specialized provision for electronic evidence and is not relevant to the physical obstruction of a harbour or the causal link to a sea wall. Option (2): "Section 47". Section 47 deals with opinion as to handwriting. This is clearly unrelated to the scenario described, which involves physical structures and environmental effects. Option (3): "Section 46". This is the correct option. Section 46 of the Indian Evidence Act is titled "Facts bearing upon opinions of experts". It states: "Facts, not otherwise relevant, are relevant if they support or are inconsistent with the opinions of experts, when such opinions are relevant." In our scenario, the question of whether a sea wall caused an obstruction would likely involve expert opinion. The fact that other similar harbours *without* such sea walls also got obstructed at the same time is a fact that is *inconsistent with* the opinion that the sea wall was the cause, or it *supports* an alternative expert opinion that a common environmental factor (e.g., a storm, unusual tidal activity) was the cause. Therefore, this fact becomes relevant under Section 46 because it directly bears upon the expert opinion regarding causation. Option (4): "Section 45". Section 45 deals with "Opinions of experts". It states that when the Court has to form an opinion upon a point of foreign law, science, or art, or as to identity of handwriting or finger impressions, the opinions upon that point of persons specially skilled in such foreign law, science or art, or in questions as to identity of handwriting or finger impressions are relevant facts. While expert opinion itself would be relevant to determine the cause of obstruction (under Section 45), the *specific fact* provided in the question (about other harbours) is not an expert opinion itself, but rather a fact that *influences* or *challenges* an expert opinion. Hence, Section 46, which deals with facts *bearing upon* expert opinions, is more appropriate for the given scenario.