A uniform ladder 5m long, weighing 300N, rests with its upper end against a smooth vertical wall and its lower end on a rough horizontal floor. The ladder makes an angle of 60∘ with the floor and is just on the point of slipping. What is the minimum coefficient of static friction between the ladder and the floor?
a) 0.50
b) 0.58
c) 0.29
d) 0.25