A Composite Beam Is Made Up of a 90 Mm $\left.E_{s}=190 \mathrm{GPa}\right)$

A composite beam is made up of a 90 mm ⫻ 160 mm wood beam . Allowable stresses in wood and steel are 6.5 MPa and $\left.E_{s}=190 \mathrm{GPa}\right)$ $\left(E_{w}=11 \mathrm{GPa}\right)$ and a steel bottom cover plate (90 mm ⫻ 8 mm,
110 MPa, respectively. The allowable bending moment about the z axis of
The composite beam is most nearly: (A) $2.9 \mathrm{kN} \cdot \mathrm{m}$
(B) $3.5 \mathrm{kN} \cdot \mathrm{m}$
(C) $4.3 \mathrm{kN} \cdot \mathrm{m}$
(D) $9.9 \mathrm{kN} \cdot \mathrm{m}$