有如下VB程序:

Dim i As Integer, j As Integer, k As string, n As Integer

n = 3

List1.Clear

For i=1 To n

k =″″

For j=1 To i

k = k+″*″

Next j

List1.AddItem k

Next i

该程序运行后, 在列表框List中显示的是（   ）

A：

B：

C：

D：