单选题
有如下通用过程：
Function Fs(ByVal n As Long) As Long
Dim k As Long
k = 1
n = Abs(n)
Do While n
k = k * (n Mod 10)
n = n / 10
Loop
Fs = k
End Function
编写如下事件过程：
Private Sub Form_Click()
Dim a As Long
Dim b As Long
a = InputBox("请输入一个数")
a = CLng(A)
b = Fs(A)
Print b
End Sub
程序运行后，单击窗体，在输入对话框中输入567，输出结果为