If there is a deposit of ＄20 billion of new currency into the banking system, excess reser

If there is a deposit of ＄20 billion of new currency into the banking system, excess reserves will increase by ______.

A．＄2 billion.

B．＄18 billion.

C．＄20 billion.

D．＄48 billion.

请帮忙给出正确答案和分析，谢谢！