Though the Effective Depth of a T-Beam Is the Distance

Though the effective depth of a T-beam is the distance between the top compression edge to the centre of the tensile reinforcement, for heavy loads, it is taken as

A) 1/8^th of the span
B) 1/10^th of the span
C) 1/12^th of the span
D) 1/16^th of the span