The correct answer is "C. all of history has been a struggle between classes of people."
Karl Marx was a German economist and socialist revolutionary who developed the theory of Marxism, which states that societies have developed a long time through <em>class struggle</em>. He attributes this to <em>capitalism</em>, where the ruling classes, which control the means of production enter in conflict with the working classes, also known as <em>"the proletariat"</em>. This constant struggle would eventually lead to the fall of capitalism and the rise of a new system called <em>socialism</em>.
<span>Advanced mathematics was critical to the development of the Mayan calendar. The Maya needed a system of mathematics to record celestial movements over the years, to handle large numbers, and to calculate the solar and lunar year with great precision.</span>
