如图所示的VB程序中，输入以下程序代码，运行后单击命令按钮Command1，出现错误的提示图是：（ ）

Private Sub Command1_Click()
Dim a(1 To 4) As Integer
Dim i As Integer
a(1) = 1
For i =" 2" To 4
a(i) =" 2" * a(i - 1) + 1
Next i
List1.AddItem Str(a(i))
End Sub

A．

B．

C．

D．