To mark all contents of a folder as read, you would:

A.

Click the Folder tab and choose mark all as read from the clean-up group

B.

Press Ctrl + Alt + R

C.

Click the filter email button and choose Mark All

D.

None of the above

Correct answer is A

To mark all contents of a folder as read, you would click the Folder tab and choose "mark all as read" from the clean-up group. This option is specifically designed to mark all the unread messages in a folder as read, allowing the user to easily manage their inbox and keep track of important emails.

The other options listed (Press Ctrl + Alt + R and Click the filter email button and choose Mark All) are not the correct methods to mark all contents of a folder as read.