Which type of writing primarily aims to inform the reader?

The best choice for the type of writing that primarily aims to inform the reader is expository writing. This form of writing is characterized by its objective approach, presenting detailed information, facts, and explanations about a particular topic without the writer's opinions or biases. It is designed to educate the audience by providing clear and straightforward information, often incorporating examples, statistics, and analysis to support the content.

In contrast, persuasive writing seeks to convince the reader to adopt a particular viewpoint or take action, while descriptive writing focuses on detailing sensory impressions to paint a vivid picture for the reader. Narrative writing, on the other hand, tells a story and centers on character development and plot rather than simply informing. Therefore, expository writing is distinct in its intention to inform, making it the correct answer.