How to handle back talk?

My son is 3 years old and lately he’s been talking back whenever asked/redirected to do something. Worst of it was today, we were in the store and he was grabbing things off of the shelf and throwing it on the floor. I told him to stop, and asked him to pick up the things he threw. He proceeded to throw things and say “quit talking to me” I picked up the things and we left immediately. I’m not sure how to handle this anymore, it’s so frustrating. What should I do?