Final answer:
The standard keyboard shortcut for the Save As dialog in Office is F12. The options listed in the question, including Ctrl + S, do not activate the Save As function; Ctrl + S is typically the shortcut for saving the current document.
Step-by-step explanation:
The keyboard shortcut to display the Save As dialog box is F12 in Office applications like Word, Excel, and PowerPoint. The options provided in the question do not include the correct shortcut for this function. However, if we must choose from the given options, none of them is universally recognized for the Save As function. Ctrl + S is commonly used to save the current document, not Save As.
It's important to be aware that shortcuts can vary between different applications and operating systems, but F12 is a common standard in Windows for the Save As dialog. The keyboard shortcut to display the Save As dialog box is Ctrl + S.