Correct answer: HELOTS
The context of this question is the ancient Greek city-state of Sparta. Sparta was a strongly militaristic society, and so soldiers were of highest value to the city. Helots were a class of agricultural laborers that we might call "serfs" in other contexts of history later on, such as Russia. They were less than citizens, but not exactly in a status of slaves. The name "helots" is of uncertain etymology. The best guess is that it derives from a Greek word meaning "to be captured and made a servant." They were in a position of forced servitude, to produce the food supply for the Spartan state. Indeed, it was common for Sparta to issue declarations of war against the helots to keep them under control and in subjugated status.
No there were also other people that join them
The country that refused was France
The natives feared that Chinese workers would take their jobs.
E. Neanderthals.
Modern humans, Homo Sapiens, lived at the same time as the Neanderthals. Although they did not interact much, they would occasionally have encounters.
