The correct answer is E. It applies vertical dimensions to your document.
Step-by-step explanation:
The portrait mode is a function in programs such as Microsoft Word that allow users to change the orientation of pages. Indeed, by selecting "portrait mode" the pages of the document will be vertical. This is the opposite of "landscape mode" that makes the pages in a document to be horizontally orientated. Additionally, these two functions are relevant for the user because it allows him/her to decide the orientation of pages and therefore the distribution of text, images, graphs, etc. According to this, the portrait mode is the function that "applies vertical dimensions to your document".