Development of farm sector gives a boost to secondary sector and development of both primary and secondary sectors give a boost to tertiary sector. This is called the product contribution of agriculture.

• Product contribution of agriculture: This concept refers to the idea that a thriving agricultural sector can stimulate growth in other sectors of the economy. Here's how it works:
-A well-developed farm sector provides raw materials for the secondary sector (industries) to process into finished goods.
-Increased agricultural output and industrial production together lead to a rise in incomes and demand for services, boosting the tertiary sector (services).
Ragnar Frisch: A prominent economist who is credited with coining the term "product contribution of agriculture."

📌 Other Options Explained:
-(b) Adam Smith: While Adam Smith's work laid the foundation for classical economics, he is not associated with this specific concept.
-(c) J. M. Keynes: John Maynard Keynes was a key figure in macroeconomics, but not directly related to this term.
-(d) Simon Kuznets: Simon Kuznets is known for his work on economic inequality and development, not this agricultural concept.