C4 W3 Quiz! The answer is wrong about the Question below. Thanks for all of your suggestions in advance!

Andrew Ng mentioned that we need 2N+1 positions for Landmark detetcion because we always need a variable (face?) predicting if this is a face first, then positions for l1x, l1y…lnx,lny, right?
Then what does this question’s answer mean?

Please provide the video name and time mark where Andrew discusses this.

This was discussed in a previous thread (found by searching for the keyword “landmark”):