Needs will give points to who gives out an honest answer

The correct answer is the last option - Add to Document.

When you choose to add the envelope to the document it adds the envelope as the first page of the document. When printing you can either print it as part of the document, or customize your printing to only print the envelope or the letter individually.

answer is:

a). backstage view

explanation:

backstage view is the area where files and data about them is managed— creating, saving, printing, sending to others, inspecting for hidden metadata or personal information, and setting options. so in this way we can add many things to our document swiftly.

i hope you get the idea.