Your application includes a collection of Product entities named products. A Product property named Category gives the product category. You need to create a LINQ query to return an object that contains each unique category name along with a list of all products in that category.

Which query should you use?

Use the group by operator to create a LINQ query to return an object than contains each unique category name along with a list of all products in that category. Specify a return type that includes the grouping Key (Category in this case) and the entities in the group.

This query's return type is g.Key. This will return just a list of category names, without the associated products:

from p in products
group p by p.Category
into g select g.Key;