In the federal system, allowing lower-level governments to ? try out? new policies on a local level is generally referred to as of democracy.?

In the federal system, allowing lower-level governments to 'try out' new policies on a local level is generally referred to as laboratories of democracy.
This is because in a laboratory, scientists try out many things and always experiment so as to get as many results as possible. Similarly, these governments try out different things in order to make their community a better place.

Ithink the answer is d.