In a scarce$-$reserves regime, banks hold while in an abundant$-$reserves regime, banks hold $$ What is the IORB, and what role does it play in the difference between the two regimes?

A$.$ The IORB is the interest rate the Fed pays banks on their reserves at the Fed; the higher the IORB, the fewer loans banks make, and the money supply will be lower.

B$.$ The IORB is the interest rate used by major global banks when they lend to each other; the higher the IORB, the fewer loans banks make, and the money supply will be lower.

C$.$ The IORB is the interest rate the Fed pays banks on their reserves at the Fed; the higher the IORB, the more loans banks make, and the money supply will be higher.

D$.$ The IORB is the interest rate used by U$.$S$.$ banks when they lend to each other; the higher the IORB, the more loans banks make, and the money supply will be higher.