How do we use relative pronouns? When do we use them?

Explanation:

You use them when starting a relative clause for example: John was driving his car which is new.

In bold it says which, which is one of the relative pronouns that you use to add a relative clause

i think the answer is d.

the statement that best explains why the tenth amendment reserves some rights and powers to states is that the framers believed in the principle of federalism. this principle says that some powers are in the hands of a centralized national government, while others are reserved for the governments of several states.