You are creating a Windows Presentation Foundation browser application by using Microsoft .NET Framework 3.5.
The application contains a PageFunction class named CustomerPage.
You need to ensure that the CustomerPage page function can perform the following tasks:
* Accept a customer ID in the form of a string.
* Allow the user to update customer information on the page.
* Return an instance of a Customer object with the updated information.
Which class definition should you use?

A.
public partial class CustomerPage : PageFunction<string>
{
public CustomerPage(string CustomerID)
{
…
}
}

B.
public partial class CustomerPage : PageFunction<Customer>
{
public CustomerPage(string CustomerID)
{
…
}
}

C.
public partial class CustomerPage : PageFunction<string>
{
public CustomerPage()
{
…
}
private Customer ReturnCustomer(string customerID)
{
…
}
}

D.
public partial class CustomerPage : PageFunction<Customer>
{
public CustomerPage()
{
…
}
private Customer ReturnCustomer(string customerID)
{
…
}
}