My nephew's gotten to that point too. We taught him VERY young about different TYPES of things. He didn't just learn "This is a car". He learned "This is a Volkswagon beetle. That's a Chevy Cruz, etc." He didn't learn "This is a pepper." He learned "This is a green bell pepper, that is a red bell pepper, that is a jalepno pepper, that is a chili pepper...."
The downside is now he thinks EVERYTHING has different types, and always seems to assume there's something more specific you could tell him.
I've started to get a bit better at dealing with it, by intentionally being as vague as possible on the first question.
ex:
Recently they dropped me off at my place and came in for a bit. He saw this photo, which I have affixed to my animation desk:
Dexter: "Whos that?"
Me:" Those are hockey players." (He
knows this. He's pretty nuts about hockey, actually.)
Dexter:"What kind of hockey players?"
Me: "Women hockey players."
Dexter: "What kind of women hockey players?"
Me: "Canadian women hockey players."
Dexter: "OK"
Thankfully that appeased him, cause I wasn't sure where I would have gone after I got to "Olympic. Gold. Medal Winning. Canadian. Women. Hockey. Players."
His junior kindergarten teacher is going to have fun with him in the fall.