A beam with a rectangular section of 120mm× 60mm,designed to be placed vertically is placed horizontally by mistake. If the maximum stress is to be limited, the reduction in load carrying capacity would be
(a)$\frac{1}{4}$ (b)$\frac{1}{3}$
(c)$\frac{1}{2}$ (d)$\frac{1}{6}$