They experienced illness, the cold winter and shortages of supplies
The idea of the social contract theory comes from Jean Jacques Rousseau's book the Social Contract but one of the most prominent philosophers that discussed the idea was Thomas Hobbes who describes social contract as a contract between the individuals and the government, whose authority comes from the people. The people would cede some of their rights to the government for protection and the sovereign is bound by the wishes of the people as it is they that govern his decisions.
So the question of John Stuart Mill relate to the theory of the social contract very much. The main issue is exactly how many rights would the people have to cede and what would be the right balance between the independence and the obedience to the social contract. That is a very thin and tricky line to navigate.
For Rachel the answer is c
