Answer:
Option B is the correct answer.
Explanation:
Shear stress is the ratio of shear force to area.
We have
Shear stress = 3 N/mm² = 3 x 10⁶ N/m²
Area = Area of rectangle = 10 x 10⁻² x d = 0.1d
Shear force = 50000 N
Substituting
[tex]\texttt{Shear stress}=\frac{\texttt{Shear force}}{\texttt{Area}}\\\\3\times 10^6=\frac{50000}{0.1d}\\\\d=0.1667m=16.67cm[/tex]
Width of beam = 16.67 cm
Option B is the correct answer.