Question

which step is first in changing the proofing language of an entire document?
click the language button on the status bar.
select the whole document by pressing ctrl+a.
under the review tab on the ribbon in the language group, click the language button and select set proofing language.
run a spelling and grammar check on your document before changing the language.

Explanation:

To change the proofing language of an entire document, the first step is to select the whole document. This is because you need to apply the language change to all the text in the document. Pressing Ctrl+A is the standard way to select all content in a document in many applications.

Answer:

Select the whole document by pressing Ctrl+A.