以下代码输出的是:Import numpy as npA = np.array(1,2,3],4,5,6]])Np.append(a, 7,8,9])Print (np.append(a, 7,8,9]],axis = 0))
选项：

A: 1 2 3] 4 5 6]]
B:1 2 3 4 5 6 7 8 9]
C: 1 2 3] 4 5 6] 7 8 9]]
D: 1 2 3 5 5 5]4 5 6 7 8 9]]