An attorney wants to discover documents from an opposing party. However, the attorney isn't sure if the documents are discoverable. Attorney A says the documents are discoverable even if there isn't a substantial need for them, under the federal rules of discovery. Attorney B says the attorney can't discover the documents unless a substantial equivalent couldn't be obtained without undue hardship. Which one of the attorneys is right?

A. Attorney A is correct.

B. Attorney B is correct.

C. Both attorneys are correct.

D. Neither attorney is correct.