In this task, you are given a context and four options. Each option is a suggested ending for the context. You should read the context and pick the best ending for the context. Please answer with "A", "B", "C", and "D".

[header] How to write best selling children's books [title] Pick an age range. [step] You do not want to walk up to an agent or publisher with a vague idea of your target audience. Agents and editors don't take well to book's that are " for all ages. <sep> (A) " if you want to write a bestseller, it's important to have a niche age range in mind. [substeps] Things like picture books and stories with only a few words are usually for ages 2 to 6. (B) " it can be stressful to work with adults that are not yet ready for you book. [substeps] Part of the reason children's books are so popular is that they emphasize mental, emotional, and physical maturity. (C) " fifteen or more year olds will quickly start to disseminate the information to an unqualified adult who no longer has a preference for fan literature. Reading up on the latest minds before you book can help to come to an understanding of what they want from a young audience before you begin reading. (D) " instead, pick an age range to be as engaging as possible. Ask yourself why the publisher of the book ultimately wants that book.
A