[单项选择题] 在窗体上画一个名称为 Command1的命令按钮，然后编写如下事件过程： Private Sub Command1_Click()Dim a(4)As Integer, x As In

[单项选择题] 在窗体上画一个名称为 Command1的命令按钮，然后编写如下事件过程：

Private Sub Command1_Click()

Dim a(4)As Integer, x As Integer, sum As Integer

n = 4: sum = 0

a (1) = 1

For k = 0 To n - 1

For i = 1 To k + 1

x = k + 2 - i

a(x)= a(x)+ a(x - 1)

If x ＜ n - k Then Exit For

sum = sum + a(x)

Next i

Next k

Print sum

End Sub

程序运行后，单击命令按钮，则窗体上显示的内容是

A．5

B．6

C．8

D．11