Final answer:
The theory of positivism was invented by Auguste Comte. He is considered the father of sociology. Karl Marx believed that the history of society was a history of class struggles and is a central figure in the conflict theory perspective. The correct option is a.
Step-by-step explanation:
The sociologist who invented the theory of positivism is Auguste Comte. Positivism is a philosophy theory which states some positive knowledge is based on natural phenomena and their properties and relations. So, information collected from sensory experience, interpreted through reason and logic, forms the exclusive source of all such knowledge.
Comte, who is often regarded as the father of sociology, believed that like the physical world, society operated under its own set of laws. He proposed that these laws could be discovered through the application of the methods of science to the study of society, which he named positivism.
The sociological thinker who believed that the history of society was one of class struggle is Karl Marx. Marx's view is central to the conflict theory, a perspective that posits that societies change and develop due to the struggle between competing interests. When considering which founder of sociology believed societies changed due to class struggle, Karl Marx would also be the correct answer. Marx's theories about class struggle led to his critiques of capitalism and his vision of communism.
Hence, Option a is correct.