Peter works as a Software Developer for PatSoluTech Inc. He develops a Web application using Visual Studio .NET. The application contains an online ordering Web form named WebForm1. WebForm1…

Peter works as a Software Developer for PatSoluTech Inc. He develops a Web application using Visual Studio .NET. The application contains an online ordering Web form named WebForm1. WebForm1 contains several Web server controls that include a TextBox control named TextBox1 and an ImageButton control named ImageButton1. He wants data entered in TextBox1 to be validated whenever ImageButton1 is clicked. Which of the following will Peter use to accomplish the task?