The idea for a lie detector was first conceived in the early 20th century, but there were earlier concepts related to measuring physiological responses to deception. The earliest significant developments in this field are attributed to the work of Giovanni Battista Perusini and later, in the 1920s, by John Augustus Larson and others who created more sophisticated devices. However, none of your provided years (1729, 1730, 1731, 1732) are related to the conception of the modern lie detector.
If the question intended to reference the early theoretical foundation leading to lie detection, 1729 is noted in some historical contexts for discussions around physiological responses, but it does not specifically relate to the modern concept of a lie detector.
For the purpose of answering based on your options, the closest historical reference is 1729.