A) WEALTH DEFINITION This definition was given by Dr. Adam Smith and support by J. B Say and J. S Mill. First of all, in 1776, Dr. Adam Smith wrote a book named " AN ENQUIRY INTO THE NATURE, AND C AUSES OF THE WEALTH OF NATION ". He say's that, "ECONOMICS IS THE SCIENCE OF WEALTH " B) WELFARE DEFINITION: This definition was given by Prof. Alfred Marshall and supported by Prof. Pingo and Prof. Cannon. Prof. Alfred Marshall in his book " PRINCIPLE OF ECONOMICS" published in 1890 , has define economics "AS A SCIENCE WHICH STUDY MEN'S BEHAVIOR IN ORDINARY BUSINESS OF LIFE, IT ALSO ENQUIRERS THAT HOW HE EARN HIS INCOME AS WELL AS HOW HE SPEND IT" C) SCARCITY DEFINITION This definition was given by Prof. Lord Robbins and supported by Prof. Samuelson and Prof. Stigler. Prof. Robbins in his book "AN EASSY ON NATURE AND SIGNIFICANCE OF ECONOMICS SCIENCE" Published in 1932.Define economics "AS A SCIENCE WHICH STUDIES M...