Answer: vassals.
Explanation: A king (or lord) ruled large areas of land. To protect his land from invasion, the king gave parts of it to local lords, who were called vassals.
Answer:
The answer is social structure
The right answer is D. to escape persecution
The challenges that the cities faced as a result of the second industrial revolution were population explosion,traffic related problems and sanitation challenges or pollution. Population explosion came about as a result of immigration and migration factors due to the pull factor of job opportunity in these towns.