The mass of a metallic beam of uniform thickness and of length `6m` is `60kg`. The beam is horizontally and symmetrically lies on two vertical pillars which are separated by a distance `3m`. A person of mass `75kg` is walking on this beam. The closest distance to which the person can approach one end of the beam so that the beam does not tilt down is (neglect thickness of pillars)
A. `30 cm`
B. `20 cm`
C. `15 cm`
D. `10 cm`
