Y plc is attempting to forecast future events in its market. It has therefore hired a number of industry experts to identify possible developments over the next ten years. Y plc wishes to avoid any risk of the experts it has hired simply conforming with each other's opinions, so it has decided to interrogate them by questionnaire, meaning that they will never meet in person. Which ONE of the following approaches to forecasting is Y adopting? A Think tank B Brainstorming C Derived demand D Delphi method