Clear data in several dropdown lists together

I have 10 dropdown lists. I wanna click a button to clear data in 7 dropdown lists together. I know I can define 7 callback functions to do it. I wanna know whether there is better method to do it. Thanks

you could set the button as an input for a dummy div…
and have 7 callbacks with the dummy div as the input, the dropdowns as the output.

pretty tedious, should work though.