3.[单选题] 曲线ρ=sin^3(θ)/(3)(0≤θ≤(π)/(2))的弧长为（）A. (π)/(4)+(3sqrt(3))/(8)B. (π)/(2)+(3sqrt(3))/(4)C. (π)/(2)-(3sqrt(3))/(4)D. (π)/(4)-(3sqrt(3))/(8)

3.[单选题] 曲线$ρ=sin^{3}\frac{θ}{3}(0≤θ≤\frac{π}{2})$的弧长为（）

A. $\frac{π}{4}+\frac{3\sqrt{3}}{8}$

B. $\frac{π}{2}+\frac{3\sqrt{3}}{4}$

C. $\frac{π}{2}-\frac{3\sqrt{3}}{4}$

D. $\frac{π}{4}-\frac{3\sqrt{3}}{8}$