Answer: B
Correct answer: .dotx
A Word template is saved as .dotx. The t marks it as a template and the x as XML-based, matching the pattern of .docx for an ordinary document. A template stores styles, page setup, boilerplate text, headers, footers and building blocks. Opening one creates a new document based on it rather than opening the template itself, which is what keeps the original intact for reuse. Every Word document is based on a template; where none is chosen, the default Normal.dotm is used. Changing the Normal template alters the defaults for all new documents, which is why it is worth editing carefully. The macro-enabled variants are .dotm for templates and .docm for documents, separated from the plain formats for security - a .docx or .dotx cannot carry macros at all. The older binary formats were .doc and .dot.