The rate is the interest rate banks charge each other for borrowing or storing money.

I believe the answer is: Federal funds rate

There are some circumtances when the amount of money that is stored in the banks is lesser than the amount that they need to maintain their operation. In this case, they could borrow the amount of money that they need to sustain it from other banks. In return, they need to pay them back with interests. This interests is called the federal funds rate.

the correct answer on edge is

c) pair 6