设A为三阶矩阵，已知，，，则（ ）。\n \n \n \n \n \n \n

\n \n \n \n A.\n 6 \n

\n \n

\n \n \n \n B.\n －4 \n

\n \n

\n \n \n \n C.\n －2 \n

\n \n

\n \n \n \n D.\n 4\n