When the maximum vertical stress \((σ_z)_{max}=\frac{0.0888Q}{r^2}\) at a point, the shear stress at that point is ____________

• A. \(τ_{rz}=\frac{0.0888Q}{r^2} \)
• B. \(τ_{rz}=\frac{0.0725Q}{r^2} \)
• C. \(τ_{rz}=\frac{0.234Q}{r^2} \)
• D. \(τ_{rz}=\frac{0.328Q}{r^2} \)