Design of R.C.C. simply supported beams carrying U.D.L. is based on the resultant B.M. at

ANS:B - mid span

The design of reinforced concrete (R.C.C.) simply supported beams carrying a Uniformly Distributed Load (U.D.L.) is based on the resultant Bending Moment (B.M.) at mid span. For simply supported beams subjected to a U.D.L., the maximum bending moment typically occurs at the mid-span of the beam. This is due to the symmetrical nature of the loading condition, where the load is uniformly distributed over the entire span of the beam. As a result, the beam experiences the highest bending moment at its midpoint. Designing based on the maximum bending moment at mid-span ensures that the beam can safely withstand the applied loads without experiencing excessive deflection or failure.