如下数组声明语句中不正确的是 A.

int[ , ] a=new int[4,2]{{1,2},{3,4},{5,6},{7,8}}; B.

int[ , ] a=new int[ , ]{{1,2},{3,4},{5,6},{7,8}}; C.

int[ , ] a={{1,2},{3,4},{5,6},{7,8}}; D.

int[ , ] a;
a={{1,2},{3,4},{5,6},{7,8}};