Question

what started the modern agricultural revolution?
new types of crops
improved farming methods
greater demand for food
more fertile soil

Explanation:

The modern Agricultural Revolution was mainly initiated by the need to meet the growing population's food requirements. A greater demand for food drove innovations in agriculture. New crop types, improved farming methods, and more fertile soil could be outcomes or means to address the demand, but the root cause was the greater demand for food itself.

Answer:

greater demand for food