What was one major reason for agricultural expansion in the Later Vedic period?

Correct answer: Use of iron tools

The wider use of iron tools, especially axes and plough-related implements, helped communities clear forests and cultivate heavier soils in parts of the Ganga valley. Iron was not the only reason for agricultural expansion; population growth, settlement, political change, and other technologies also mattered. Nevertheless, it was an important enabling factor. Paper, railways, and printing presses belong to much later periods.