You are creating a Windows Forms application by using the .Net Framework 3.5.You plan to display detailed help instructions for each control in the form.You create a help file.You configure a HelpProvider component on the form.You need to display the help file for the control that is focused when the F1 key is pressed.Which method of the HelpProvider class should you call for each control？（）

A.SetShowHelp
B.SetHelpString
C.SetHelpKeyword
D.SetHelpNavigator