I have done my research and checked my textbooks it is C
Their progress and wealth is highly dependent on the harvests, and the price of grain. They probably have to import some industrial products and if they had a bad year (weather, other catastrophies, poor technology) they can't get the necessary amount of industrial products in exchange for their surplus e. g. in grain. There are so many standards and requirements about the quality of food production that no country can survive solely on agriculture without high quality technology (machines, unharmful fertilizers, research-based breeding, etc.).
1 - The flow of the river may change as water is fed out into tributaries. 2- As a river flows it may etch out the river bed and create a gulley as it moves sediment and debris. 3- Depending on the speed of a stream it can form into a meandering river with twists and turns. What is interesting about these rivers is they actually move as debris is deposited on one side of the meander and picked up on the other. 4 - Depending on topography the river may increase in speed and give you rapids.
