单项选择题

在窗体上画一个命令按钮,然后编写如下程序:
Private Sub Command1_Click()
Dim n As Integer
n=InputBox("请输入一个数")
Print fun1(n)
End Sub
Function fun1(ByVal Bum As Long) As Long
Dim k As Long
k=0
Bum=Abs(Bum)
Do While Bum
k=k+(Bum Mod 10)
Bum=Bum\10
Loop
fun1=k
End Function
程序运行后,单击命令按钮,在输入对话框中输入234,输出结果为______。

A) 3
B) 4
C) 9
D) 10