What factors enabled the city to survive foreign attacks for hundreds of years before finally falling?

Which of the following answer best explains the ideals or principles led to the concept of manifest destiny? a americans wanted the european countries to stay out of the north american continent. b americans felt they had a god-given duty to protect the land of the native americans. c americans thought they had a god-given duty to spread their culture and government. d americans learned about this concept from the native americans tribes had encountered.