Answer:
Reasons tell why something is so.
Examples prove your point with specific facts.
Incidents give proof with actual circumstances.
Explanation:
In any composition writing, paragraphs and statements are arranged in such a way that they provide the best feel of what the topic is about. It also enables the organized representation of any given topic.
And in such compositions, there are certain use/ reasons on why certain things are done. Like for example, reasons are given or added in a sentence/ statement/ paragraph to show or tell why so and so happen. Reasons provide the "why" of things, giving us useful valid points on why things happen.
Examples are a way of proving a given point. It gives added information to make the point easier to understand.
Incidents are also used as they are proof of what has happened. They give the proof, but also with evidence that explains the actual circumstances giving validity to the claim made.
