Explanation:

4th option is correct. 

• M1 is a metric for the money supply of a country and includes physical money — both paper and coin — as well as checking accounts, demand deposits and negotiable order of withdrawal (NOW) accounts. The most liquid portions of the money supply are measured by M1 because it contains currency and assets that can be converted to cash quickly.
• M2 is a measure of the money supply that includes all elements of M1 as well as "near money." M1 includes cash and checking deposits, while near money refers to savings deposits, money market securities, mutual funds and other time deposits.
• M3 is a measure of the money supply that includes M2 as well as large time deposits, institutional money market funds, short-term repurchase agreements and other larger liquid assets.
• M4: M3 + Commercial Paper

Note: The liquidity means how fast an instrument can be converted into cash. The liquidity of these measures are in order M1>M2>M3>M4 i.e. M1 is most liquid and M4 is least liquid.