The foremost role of money is :

Medium of exchange

The correct answer is option (3) : Medium of exchange

The foremost role of money as a medium of exchange is rooted in its function as a widely accepted intermediary in transactions. Money facilitates the buying and selling of goods and services by serving as a commonly recognized and accepted medium for trade. It eliminates the need for a barter system, where individuals would have to exchange goods and services directly.

Here's a brief explanation of the options:

1. Unit of Account: Money serves as a standard measure for expressing the value of goods and services. This helps in comparing and measuring the worth of different items.

Here's a brief explanation of the options :

1. Unit of Account : Money serves as a standard measure for expressing the value of goods and services. This helps in comparing and measuring the worth of different items.

2. Measure of Deferred payment : Money is used as a standard for future transactions. It allows individuals to enter into contracts that involve payments over time.

3. Medium of Exchange : This is the most fundamental role. Money acts as a medium through which goods and services are exchanged. It is widely accepted in transactions, making trade more efficient.

4. Store of Value : Money can be saved or stored for future use. It retains its value over time, allowing individuals to store wealth and make purchases in the future.

While all these functions are important, the primary and most fundamental role of money is its function as a medium of exchange.