Conrad, please forgive me. But are we talking about the same scenario ? Consider the following picture after import:

There a four people, each having a suggestion. Assume, that they are all correct (which they aren't). Where do I have to click to accept them all ? What do you mean by "check mark that appears after the question mark" ?
Oh, now I see. No need to apologize, since your picture shows me that I assumed you were in a different view...that's my fault. I thought you were in People view, but you're in Loupe view with faces shown. So I was explaining something you weren't seeing.
To select multiple faces and accept them all at once, Lightroom needs to be in People view (choose View > People). That's the grid view shown in my earlier post. You can also enter People view by clicking the button next to the red arrow below, in the Toolbar at the bottom of the window (if it isn't showing, press the T key). The view you've been in is Loupe (single image) view with faces highlighted, indicated by the icon next to the red A below.

Unfortunately, I don't know of a way to accept all of the faces at once in Loupe view. If there is a way, someone else will need to tell us.
I answered the way I did because I had been working in People view recently, so I wasn't thinking of the view you're working in. People view shows faces found in any photos within the currently active folder or collection, so I like it because of that ability to accept or reject the same face across many photos at once.