单项选择题

有如下程序:  Private Sub Commandl_Click()   Dim a As Integer   a=2   For i=1 To 3     Print Gad (a)     Next i  End Sub  Function Gad (a As Integer)   b=0   Static c   b=b + 1   c= c + 1   Gad= a + b + C  End Function  运行上面的程序后,单击命令按钮,输出结果为

A.1   2   3
B.2  3  4
C.4  5  6
D.1  4  6