There is a saying that coming events cast their shadows before. (1) ______ it is not universally true. Something can happen within a second, and one may not (2) ______ it. (3) ______ some instances show that predictions based on certain signs have gone wrong. People generally say that natural calamities can be predicted by observing the animals. But what if animals are suffering from some disease and don’t show any signs before the event appears? They may fail to make peculiar sounds or actions about the events which are going to take place. (4) ______ some unnatural calamities that are likely to appear may forecast their shadows by some bad omens. (5) ______ we should not completely cancel out the possibilities that animals can sense certain unnatural happenings.

Select the most appropriate option to fill in blank number 2.

The correct answer is foresee.

Let's analyze the context of the sentence containing blank number 2: "Something can happen within a second, and one may not (2) ______ it."
The passage discusses the concept of predicting or sensing events before they occur ("coming events cast their shadows before").
If something happens extremely quickly (within a second), a person or observer would not be able to predict, anticipate, or see it coming beforehand.
Let us evaluate the given options in this context:
1. foresee: To be aware of or predict an event before it happens. This fits the context perfectly, as one cannot foresee an event that occurs in a split second.
2. rescind: To revoke, cancel, or repeal a law, order, or agreement. This is irrelevant to predicting events.
3. legalise: To make something permissible by law. This is unrelated to the context of predictability or sudden occurrences.
4. affect: To make a difference to or influence something. While grammatically possible, it does not align with the passage's central theme of predictions and warnings.
Therefore, "foresee" is the most appropriate word to fill in blank (2).