Argument: 'Every item in this consignment was checked by the packing supervisor before it left the works. So every item in the consignment carries the supervisor's initials.' Which of the following, if added to the argument, would make its conclusion follow logically?

The premise gives us 'checked by her' for every item; the conclusion needs 'carries her initials'. Only a bridge running from checking to initialling in every case closes that gap, and the correct option supplies exactly that. 'Some' is too weak to cover every item, the third option runs the bridge the wrong way, and the fourth adds nothing about initials at all.