You are implementing an ASP.NET application that includes a page named TestPage.aspx. TestPage.aspx uses a master page named TestMaster.master. You add the following code to the TestPage.aspx code-behind file to read a TestMaster.master public property named CityName. protected void Page_Load（object sender， EventArgs e） { string s = Master.CityName； }  You need to ensure that TestPage.aspx can access the CityName property. What should you do？（）

• A、Add the following directive to TestPage.aspx. <%@ MasterType VirtualPath="~/TestMaster.master" %><%@ mastertype="" virtualpath="~/TestMaster.master">
• B、Add the following directive to TestPage.aspx. <%@ PreviousPageType VirtualPath="~/TestMaster.master" %><%@ previouspagetype="" virtualpath="~/TestMaster.master">
• C、Set the Strict attribute in the @ Master directive of the TestMaster.master page to true.
• D、Set the Explicit attribute in the @ Master directive of the TestMaster.master page to true.