The book 'An Enquiry into the Nature and Causes of the Wealth of Nations' is written by;

Adam Smith

The correct answer is Option (3) → Adam Smith

Adam Smith is regarded as the founding father of modern economics (it was known as political economy at that time). He was a Scotsman and a professor at the University of Glasgow. Philosopher by training, his well known work An Enquiry into the Nature and Cause of the Wealth of Nations (1776) is regarded as the first major comprehensive book on the subject. The passage from the book. ‘It is not from the benevolence of the butcher, the brewer, of the baker, that we expect our dinner, but from their regard to their own interest. We address ourselves, not to their humanity but to their self-love, and never talk to them of our own necessities but of their advantage’ is often cited as an advocacy for free market economy. The Physiocrats of France were prominent thinkers of political economy before Smith.