单项选择题

对于如下程序,单击Co皿andl事件发生后,窗体上显示的内容为 ______。
Private Sub Command1_Click()
Dim i As Integer,a a As Integer
Do While i<20
Do While True
If i Mod 10 = 0 Then
Exit Do
Else
i=i-1
End If
Loop
i=i+11
a=a+1
Loop
Print a
End Sub

A.21
B.32
C.33
D.11