A.
$\frac{1}{3}(2\alpha_{1}+2\alpha_{2}-\alpha_{3}),\frac{1}{3}(2\alpha_{1}-\alpha_{2}+2\alpha_{3}),\frac{1}{3}(\alpha_{1}-2\alpha_{2}-2\alpha_{3})$
B.
$2\alpha_{1}+2\alpha_{2}-\alpha_{3}, 2\alpha_{1}-\alpha_{2}+2\alpha_{3}, \alpha_{1}-2\alpha_{2}-2\alpha_{3}$
C.
$\frac{1}{3}(2\alpha_{1}-2\alpha_{2}-\alpha_{3}),\frac{1}{3}(2\alpha_{1}+\alpha_{2}+2\alpha_{3}),\frac{1}{3}(\alpha_{1}-2\alpha_{2}-2\alpha_{3})$
D.
$2\alpha_{1}-2\alpha_{2}-\alpha_{3}, 2\alpha_{1}+\alpha_{2}+2\alpha_{3}, \alpha_{1}-2\alpha_{2}-2\alpha_{3}$