Left, which is a mistake? (3,5)

I believe the answer is:
not right
But I can't explain it at all! Could you help me understand?
(Other definitions for not right that I've seen before include "Incorrect" , "Wrong" .)

I believe the answer is:
not right
But I can't explain it at all! Could you help me understand?
(Other definitions for not right that I've seen before include "Incorrect" , "Wrong" .)