C) China’s presidents did not have enough power
The simple answer here is because of slavery.
The correct answer is: "He developed mathematical principles"
René Descartes (1596 – 1650) was a French philosopher, mathematician, and scientist who lived more than 20 years in the Dutch Republic and was one of the main figures of the Dutch Golden Age.
His great influence in mathematics has been his major contribution to the Scientific Revolution, although his work in philosophy is outstanding too. He developed the the Cartesian system of coordinates. He is considered the father of analytical geometry, which connects both algebra and geometry and which has been used in the development of infinitesimal analysis and calculus .
The correct answer is "C"
The key period in relation to important food exchange is between the fourteenth and seventeenth centuries. Throughout this period, Marco Polo's trips to the Far East took place, as well as the series of geographical expeditions and colonial enterprises initiated by Portuguese navigators and which continued with the voyages to America that Christopher Columbus began in 1492. The exchange of Food between Europe and America was given from the time of colonization and is not one of the causes of the independence revolutions in Latin America.
The romans had better weapons than most of the other armies
