单项选择题

在窗体上画一个名称为Command1的命令按钮,然后编写如下事件过程: Private Sub Command1_Click() Call sub1(-15.1,2.54) End Sub Public Function sub1(a As Integer,ByVa1 b As String) As Integer a=Val(b) sub1=a Print sub1 End Function 程序运行后,单击命令按钮,在窗体上输出的是

A.3
B.2
C.-15
D.提示出错