Answer:
letter to the editor of a newspaper
Step-by-step explanation:
The expository writing is a type of text that aims at the presentation of a concept or an idea.
Very often this type of writing is approached in the context of a letter to the editor of a newspaper, since it includes information about a specific object or fact, its description and the enumeration of its characteristics.
In the expository writing, the central objective of the speaker (emitter) is to explain about a subject, from resources such as conceptualization, definition, description, comparison, information and enumeration.