Acollection of money from a group of investors used to buy different investments is a
stock
mutual fund
money market
high-yield savings account

A collection of money from a group of investors used to buy different investments is called mutual funds. 
When you join in a mutual funds, you are investing your money to a markets of investments to be able to gain money over time. You buy different investments and sell them when the price gets higher.

The answer would be

The federal reserve took an expansionary approach during the crisis. this was done by expanding the money supply and boosting liquidity. this can be seen in the fed's actions of lending to banks, purchasing securities, and lowering the federal funds rate in order to lower overall interest rates. the fed's goal was to increase consumer spending and overall liquidity within the system, and they pursued this by expanding the supply of liquid money.