How can I deal with my parents' constant nagging?

This isn’t the sort of thing where I’m not listening so they have to keep telling me to do things. This is true nagging. They tell me to do one thing, and if I have not started the one thing in a minute, they tell me to do it again, and again, and again. They also do this thing when they tell me to do one chore, such as cleaning my room, and when I am still doing that, they tell me to do another thing, like doing my laundry, and when i start doing that instead, I get yelled at for not cleaning my room! What should I say or do?