The money stock in the economy is:​ a. ​the amount of wealth accumulating in the economy, such as currency and demand deposits. b. ​the amount of wealth accumulating in the economy, such as money market mutual funds and stocks. c. ​​the quantity of money circulating in the economy, such as money market mutual funds and stocks. d. ​the quantity of money circulating in the economy, such as currency and demand deposits.