单项选择题 YouarecreatingaWindowsFormsapplicationbyusingthe.NetFramework3.5.Youplantodisplaydetailedhelpinstructionsforeachcontrolintheform.Youcreateahelpfile.YouconfigureaHelpProvidercomponentontheform.YouneedtodisplaythehelpfileforthecontrolthatisfocusedwhentheF1keyispressed.WhichmethodoftheHelpProviderclassshouldyoucallforeachcontrol？（）