Can anyone tell me where to fine this?

Hey Ronald,

I'm not sure to which question you are referring? There are two fill-in-the-blank ones when I run the quiz.

One asks about grouped objects and that they are "stacked within a single _____________" This one is answered at 0:30 seconds in the video.

I'm guessing it's the other one:

"When you group the object it creates ____________ in your layers path"

Mat does sort of cover this at 2:30 to about 3:20, but it's not very clearly or explicitly explained. I normally don't give out answers directly, but in this case...
The word you're looking for is sublayers. Like I said, he does mention it, but doesn't really point out in the video that these sublayers are what is inside the layers path.

I hope this helps clear it up. :)

Enjoy the rest of the course.