Correct answer is B. Though, its a hit-n-trial method.
option A: There is no such possibility, as it is given that there are no twins, so S and G must be consecutive.
option B.For some combination of ages of SGHI we can satisfy (1) condition like taking ages as, S=5 G=5 H=3 I=1, (2) and (3) are also satisfied. So, all the 3 conditions are satisfied.
option C: IGSH, so I > G and S > H (as there are no twins) and so I + S > G + H - violates condition 1.
option D: IHSG, so I > H and S > G and so I + S > H + G - violates condition 1.