You are creating a Windows Workflow Foundation custom activity class named UpdateCustomersActivity by using Microsoft .NET Framework 3.5.

You write the following code segment in the class.
IList _customerList = new List<int>();
public IList CustomerList
{
get { return _customerList; }
}

The custom activity uses the WorkflowMarkupSerializer class.

You need to ensure that the customer list does not appear in XAML when the custom activity is serialized.

What should you do?

A.
Apply the following attribute to the _customerList field. [NonSerialized]

B.
Apply the following attribute to the CustomerList property. [DesignOnly(true)]

C.
Apply the following attribute to the CustomerList property. [DesignTimeVisible(false)]

D.
Apply the following attribute to the CustomerList property.
[DesignerSerializationVisibility(DesignerSerializationVisibility.Hidden)]