Use each of the following figures only once and form three groups. The three groups so formed are: 
(1,4,7), (2,5,8), (3,6,9)
(1,5,7), (2,4,8), (3,6,9)
(1,4,7), (3,5,8), (2,6,9)
(1,4,7), (2,6,8), (3,5,9)
Select the option that gives the number missing from the following figure. 