How did the astrolabe european explorers?
a. it enabled explorers to determine their position.
b. it allowed sailors to steer their ships better.
c. it was an instrument used to show a ship's speed.
d. it was an atlas containing detailed maps of all known lands.

The answer is given by the first choice: letter A. The astrolabe helped European explorers to determine their positions properly. An astrolabe is an instrument that is used to determine the latitude when in navigation. It was used by astrologers, navigators and astronomers during the earlier times. 

mesopotamian code of hammurabi

and i think its 1860 b.c. you mean lol

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.