The centre of mass of three particles of masses `1 kg, 2 kg and 3 kg` is at `(3, 3, 3)` with reference to a fixed coordinate system. Where should a fourth particle of mass 4 kg be placed, so that the centre of mass of the system of all particles shifts to a point `(1, 1, 1)`?
Options:
(a) `(-1 -1 -1)`
(b) `(-2 ,-2 ,-2)`
(c) `(2,2,2)`
(d) `(1,1,1)`