In the pre-independence era, who was the first person to discuss the concept of "Poverty line"? 

Dadabhai Naoroji

In pre-independent India, Dadabhai Naoroji was the first to discuss the concept of a Poverty Line. He used the menu for a prisoner and used appropriate prevailing prices to arrive at what may be called ‘jail cost of living’. He, therefore, appropriately adjusted this cost of living to arrive at the poverty line.