You are creating an ASP.NET Web site.  The site has a master page named Custom.master.  The code-behind file for Custom.master contains the following code segment.    You create a new ASP.NET page and specify Custom.master as its master page. You add a Label control named lblRegion to the new page.  You need to display the value of the master page’s Region property in lblRegion. What should you do？ （）

A.Add the following code segment to the Page_Load method of the page code-behind file. CustomMaster custom = this.Parent as CustomMaster； lblRegion.Text = custom.Region；

B.Add the following code segment to the Page_Load method of the page code-behind file. CustomMaster custom = this.Master as CustomMaster； lblRegion.Text = custom.Region；

C.Add the following code segment to the Page_Load method of the Custom.Master.cs code-behind file. Label lblRegion = Page.FindControl（lblRegion） as Label； lblRegion.Text = this.Region；

D.Add the following code segment to the Page_Load method of the Custom.Master.cs code-behind file. Label lblRegion = Master.FindControl（lblRegion） as Label； lblRegion.Text = this.Region；