The effective flange width of a continuous T-beam is

• A. \(b_f = \frac{l_o}{6}+b_w+ 6D_f\)
• B. \(b_f = \frac{l_o}{12}+b_w+ 3D_f\)
• C. \(b_f = \frac{l_o}{\frac{l_o}{b}+4}+ b_w\)
• D. \(b_f = \frac{0.5l_o}{\frac{l_o}{b}+4}+ b_w\)