As of this writing, seems like Visual Studio still unable to provide suggestion on what namespace to import for extension methods.

I was looking into doing eager loading in EF and I am aware that I can use Include() method with lambda function. By default, it is not available and I can't remember which namespace it is located under. Of course, Visual Studio was not much help. After searching online, I found out that it is an extension method under System.Data.Entity namespace. I gotta remember from now on.