The correct answer is A. L. Robbins.
L. Robbins defined economics as a ‘science which studies human behaviour as a relationship betweeen ends and means which have alternative uses’ in his book An Essay on the Nature and Significance of Economic Science, published in 1932.
Alfred Marshall defined economics as “the study of mankind in the ordinary business of life; it examines that part of individual and social action which is most closely connected with the attainment and with the use of the material requisites of well-being.”
Joan Robinson defined economics as “the science of choice under conditions of scarcity.”
Paul A. Samuelson defined economics as “the study of how men and society choose, with or without the use of money, to employ scarce productive resources which could have alternative uses to satisfy competing wants.”
Robbins’ definition is more concise and focused on the relationship between ends and means than the other definitions. It also emphasizes the scarcity of resources, which is a key concept in economics.