A metallic rod of mass 20 kg and of uniform thickness rests against a wall while the lower end of the rod is in contact with floor. The rod makes an angle of 60° with floor. If the weight of rod produces a torque 150 Nm about its lower end, the length of the rod is (g = 10 ms⁻²)
A. 1 m
B. 2 m
C. 3 m
D. 4 m