Given the task definition and input, reply with output. 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 a mystery short story [title] Know the scope of your story. [step] A short story is usually between 5 , 000 and 10 , 000 words, but may be as long as 20 , 000 words (80 pages, double-spaced). The author h.g wells said that it's a short story if you can read it in half an hour. <sep> (A) This is because the writer must also jump from one paragraph to the next quickly, before it gets too boring to keep going. But it's slightly easier if you've got a half-hour hand. (B) To write a mystery within this limited space means that you'll have to make every word count. Furthermore, you'll have to make sure your mystery short story includes these elements : [substeps] A crime of some sort, usually a murder. (C) Even though it's seven-to-nine minutes long, a half-hour read also means you need to get the ideas of your story started as soon as possible. [title] Think of your story as a book. (D) However, it can be more complex if you think it's more complex. [title] Don't forget to answer all of the questions at the end of each page.
B