Having an ObjecType within an ObjectType

Hello,

I am trying to create an ObjectType of Product that has multiple arguments, one of which is the argument of Category that I created which is an array of strings.

What is the best way to approach this? As you can see in the picture of my sandbox, whenever I exclude the category, it works.

However, how can I query from my Category table (which I already have some items in there) in which that I can query those options to put into the category slot in my Product.

Essentially I am trying to get

(Within Arguments)

Product: {
   category:[Category]
}

This has to be within my argument as in the field it works, but as an argument to create a new Product it does not.

Any assistance would be great!