$1+7=2+6$ 
Bob sees that the license plate number of the car consists of $5$ digits: $1$, $2$, $6$, $7$, $9$. If these $5$ digits are filled in the square~$$\huge\square+\square =\square +\square $$, which number is not used?~(adapted from $$2017$$ Math kangaroo Problems, Level $$1-2$$, Question \#$$8$$) 
[A] $$1$$ 
[B] $$2$$ 
[C] $$6$$ 
[D] $$7$$ 
[E] $$9$$ 