设 $J_i=\iint_{D_i} \sqrt[3]{x-y} \mathrm{~d} x \mathrm{~d} y(i=1,2,3)$ ，其中
$$
\begin{gathered}
D_1=\{(x, y) \mid 0 \leq x \leq 1,0 \leq y \leq 1\} \\
D_2=\{(x, y) \mid 0 \leq x \leq 1,0 \leq y \leq \sqrt{x}\}, \\
D_3=\left\{(x, y) \mid 0 \leq x \leq 1, x^2 \leq y \leq 1\right\},
\end{gathered}
$$
则
A. $J_1 < J_2 < J_3$
B. $J_3 < J_1 < J_2$
C. $J_2 < J_3 < J_1$
D. $J_2 < J_1 < J_3$