For finding vertical lines we use mask of values

1.	For finding vertical lines we use mask of values
A.	[-1 -1 -1; 2 2 2; -1 -1 -1]
B.	[2 -1 -1; -1 2 -1; -1 -1 2]
C.	[-1 2 -1; -1 2 -1; -1 2 -1]
D.	[-1 -1 2; -1 2 -1;2 -1 -1]
Answer» D. [-1 -1 2; -1 2 -1;2 -1 -1]

Discussion