When an Economist Describes the "Money Supply," She Is Referring

When an economist describes the "money supply," she is referring to ________.

A) Many forms of assets that can be immediately drawn on to purchase goods and services
B) Only the physical currency in circulation that can be immediately drawn on to purchase goods and services
C) Only the bank account assets that can be immediately drawn on to purchase goods and services
D) The physical currency held by banks to pay off depositors