单项选择题

在窗体上画—个命令按钮(名称为Command1),并编写如下代码:
Function Fun1 (ByVala As Integer, b As Integer)As Integer
Dim t As Integer
t=a-b
b=t+ a
Fun 1=t+ b
End Function
Private Sub Command1_ Click()
Dim x As Integer
x=10
Print Fun1(Fun1 (x,(Fun1(x,x-1))),x-1)
End Sub
程序运行后,单击命令按钮,输出结果是()。

A.10
B.0
C.11
D.21