设 $L_{1}: x^{2} + y^{2} = 1, L_{2}: x^{2} + y^{2} = 2, L_{3}: x^{2} + 2y^{2} = 2, L_{4}: 2x^{2} + y^{2} = 2$ 为四条逆时针方向的平面曲线. 记 $I_{i} = \oint_{L_{i}}\left(y + \frac{y^{3}}{6}\right)\mathrm{d}x + \left(2x - \frac{x^{3}}{3}\right)\mathrm{d}y (i = 1,2,3,4)$ , 则 $\max \left\{I_{1}, I_{2}, I_{3}, I_{4}\right\} = (\quad)$ (A) $I_{1}$ . (B) $I_{2}$ . $(\mathrm{C})I_{3}$ $(\mathrm{D})I_{4}$