Answer:
a. the ease with which an asset is converted to the medium of exchange
Explanation:
Liquidity measures how quick an asset can be converted to cash.
Money, cash is the most liquid asset. This is why it can be easily used as a medium of exchange.
Real estate is considered illiquid because it cannot be easily converted to cash.
Stocks are relatively liquid because they can be quite easily converted to cash.
Velocity measures how many times a dollar circulates in a given year.
Money can be used to measure the intrinsic value of a commodity.