The invention of the wheel gave the Sumerians more freedom of movement, or answer D. Until the invention of the wheel, if you wanted to get somewhere, you walked or you let the current take you on a boat. If you wanted to move something, you had to physically move it the entire distance.
The wheel has also allowed modern cars to be invented, as well as a variety of other products, such as airplane landing gear, rolling luggage, and rollerskates. The wheel is truly one of the most revolutionary inventions in modern history, and for it to have had such a role in modern history is amazing.
The only other invention I can think of that has been so revolutionary after its invention has been the internet.