Society must be understood by examining distributions of power and the struggles that accompany them is known

marxism

Explanation:

According to Marx, the world is understood in terms of the power and control that a "bourgeoisie" class exerts upon the "proletariat".

The distribution of power is historically a product of earlier stages that formed: slavery, feudalism, etc and express in the capitalist world  as relationships of dominance.

The burguoise is economically and politically dominant because they own the means of production. This means they are the only capable of producing wealth and their voice in politics is the force for what the laws are enforced.

In the other hand, a proletariat, working class is made of the rest of th people who need to survive selling their labour force. Since they never take part in the decision process of the industries and factories they work at, they are permanently being exploited.

Marx identifies that there will be a permanent tension between the working class and the owners of capital and labour force. Thus a call to create a worldwide strike to transform the social life and all aspects of life through revolution.

d. i assume the underlined word is "role." reformat if it isn't.

explanation:

role is closest to part because when replacing words, "playing a vital decision," "playing a vital activity," and "playing a vital dollar" don't make logical sense. the only meaningful choice is "playing a vital part."

this fits one of merriam-webster's definitions of role: "a function or part performed especially in a particular operation or process."