This would be a perfect example of the system of barter as you are trading one book for the other. You can see from here what barter is, a trading system which involves direct exchange of goods without some kind of medium of exchange, for example money. Services can also be traded this way.
An incentive basically means a motivation to do something. A motivation for entrepreneur is to make money, therefore the correct answer is the second one: Earning money.
Hope this helps!
Going from one country to another country for job and to earn money is called foreign employment. People of Nepal go to different countries of the world for jobs and earning. ... The Nepalese labour and sweat is being used in foreign countries and there is scarcity of human power for the development of our own country.
