(I need an answer quick) Which of the following events was an important effect of declining trade along the Silk Road?
A. the rise of the Han dynasty in China
B. the development of cities along the Silk Road
C. European exploration for new routes to the East
D. a greater exchange of Chinese technology with countries in Europe

crop rotation kepy different plants in the soil instead of once constintly. when switching out plants you have different nutrients being absorbed at different speeds and different roots growing differently therfore the spoil and water flow have to adapt and carry fresh nutrients to carry the constant changes that were going on in the soil.

d. migration

its c not d   tell me if that´s correct

may i have the answer choices?