Agree with Brady & Adam on this one. Each great responses.
I'll just add that, for the most part, the URL should be for the user first and then the search engine. A lot of times brands have funk looking URLs that have numbers and symbols in them - not user friendly. So, I'd recommend adding your descriptive keyword/producA/B/C into the URL if it'll help the user understand your product and navigate your site better
Hope this helps!