There is no effect on the money multiplier as long as banks meet the required reserve ratio, so interest rates remain stable.

The money multiplier decreases, which lessens the expansion of the money supply, potentially leading to higher interest rates and reduced economic activity.

The money multiplier increases, thereby expanding the money supply more and lowering interest rates to boost economic activity.

Holding excess reserves creates an unpredictable effect on the money supply, with interest rates and economic activity affected randomly.