下面所列选项中，不能正确定义并初始化二维数组a的是（ ）。
Aint[,] a=new int[2,3]{{1,2,3},{4,5,6}};
Bint[,] a=new int[,]{{1,2,3},{4,5,6}};
Cint[,] a=new int[2,3]{1,2,3,4,5,6};
Dint[,] a={{1,2,3},{4,5,6}};
Aint[,] a=new int[2,3]{{1,2,3},{4,5,6}};
Bint[,] a=new int[,]{{1,2,3},{4,5,6}};
Cint[,] a=new int[2,3]{1,2,3,4,5,6};
Dint[,] a={{1,2,3},{4,5,6}};