Answer: A.
a light that guides you out of a dark room, illuminating the world around you
Explanation: Economics is the study of mankind in the ordinary business of life. - Alfred Marshall.
Economics is the science which studies human behavior as a relationship between ends and scarce means which have alternative uses. - Lionel Robbins. Economics comes in whenever more of one thing means less of another.
At the most basic level, economics attempts to explain how and why we make the purchasing choices we do. Four key economic concepts–scarcity, supply and demand, costs and benefits, and incentives–can help explain many decisions that humans make.