Answer: Option (c) is the correct answer.
Explanation:
A reaction which is able to occur in fraction of seconds or which is able to occur at an instant rate of time means that reaction is at a very fast rate.
Rusting of iron is not an immediate process as it occurs due to the humidity present within the air an oxide layer develops on the surface of iron. This layer formation does not occur in an instant.
Photosynthesis is a process of formation of food by the plants for themselves in the presence of air, sunlight, carbon dioxide and water.
Rotting wood also takes time and may occur over a period of month or more.
An explosion is an instantaneous process as it occurs within a fraction of seconds.
Thus, we can conclude that out of the given options an explosion is an example of a chemical reaction that occurs at a very fast rate.
