What are the rules that should be followed when using Include()?

You work as Web Developer in PassGuide.com. The company uses Microsoft .NET Framework 4
as its application development platform. You write a LINQ query that uses groupby operator. You
want to use the Include() method to eagerly load additional entities. What are the rules that should
be followed when using Include()?
Each correct answer represents a complete solution. Choose three.

A.
Apply Include() only to sub query.

B.
If the expression is of type IQueryable<T>, cast it to ObjectQuery<T> before the Include()
method is invoked.

C.
Apply Include() only to results that are entities.

D.
Apply Include() only to the final query results.

Explanation: