现有如下Sub过程： Sub fun(x es single，y as single) t = x x = t y y = t mod y End sub在窗体上添加命令按钮(cmD) ，编写如下事件过程： Private sub cmd_click( ) Dim a as single Dim b as single a = 5 b = 4 fun a, b Msgbox a & chr(10) + chr(13) & b End sub运行程序后，单击按钮，则在消息框中显示的内容为( )
A．1和1
B．1.25和1
C．1.25和4
D．5和4