单选题 下面程序运行后，输出结果是______。
Private Sub mysub(b()As Integer,Optional ByVal n As Integer=2)
For I=1 to 4
b(I)=n*I
Next I
End Sub
Private Sub Command1_Click()
Dim a(1 to 4)As Integer，I As Integer
Call mysub(a()，5)
Mysub a()
ForI=1 to 4
Print a(i);
Next
End Sub
A 1 5 10 15 20 B．2 4 6 8 C．出错 D．0 0 0 0