单项选择题

在窗体上画一个名称为Command1的命令按钮,然后编写如下程序:
Private Sub Command1_Click()
Static a As Integer,b As Integer
Cls
b = b + 3
a = a + b
Print a,b
End Sub
程序运行时,3次单击命令按钮Command1后,窗体上显示的结果为

A.8 16
B.6 6
C.15 18
D.18 9