Which one of the following represents curvature of a beam subjected to pure bending?

• A. \(\pm y'{\left( {1 + y'} \right)^{\frac{1}{2}}}\)
• B. \(\pm '{\left( {1 + y} \right)^{\frac{1}{2}}}\)
• C. \(\pm \;y''{\left( {1 + {{y'}^2}} \right)^{ - \frac{3}{2}}}\)
• D. \(\pm \;y\;'{\left( {1 + y''} \right)^2}\)