It was invented by the Sumerians, so it would be Sumer
Locke was a philospher who is claimed to be the most influential person of the Enlightment thinkers. He is also kbown for creating liberalism, and is recognized as the Father of Liberalism.
The answer to your question is:
C. Were dirty, crowded, and unhealthy.
Primary sources told an account of what actually happened because they were recorded from the actual event itself/saw the actual event
secondary sources (like our textbooks) arent 100% accurate because they are based off of the primary sources