Which type of essay focuses on explaining a topic or an idea?

The correct answer is the informative essay. This type of essay is specifically designed to educate the reader about a particular topic or concept. It presents information in a straightforward manner, often utilizing facts, statistics, and examples to clarify the subject at hand. The primary aim is to enhance the reader's understanding by conveying understanding without attempting to persuade or provide a personal story.

In contrast, persuasive essays aim to convince the reader to accept a particular viewpoint or take action, using arguments and emotional appeals. Descriptive essays focus on providing detailed sensory information about a person, place, or object, allowing the reader to visualize the subject. Narrative essays tell a story, often from the author's perspective, to share experiences and insights rather than simply explaining a concept. Each of these other types of essays serves a distinct purpose, setting the informative essay apart as the one that strictly focuses on explanation and education.