The centre of mass of a system of three particles of masses 1 g, 2 g and 3 g is taken as the origin of a coordinate system. The position vector of a fourth particle of mass 4 g such that the centre of mass of the four particle system lies at the point `(1, 2, 3)` is `alpha(hati+2hatj+3hatk)`, where `alpha` is a constant. The value of `alpha` is

Options

A. `frac(10)(3)`
B. `frac(5)(2)`
C. `frac(1)(2)`
D. `frac(2)(5)`