Answer:
So this question was actually pretty confusing so in the end I got this answer:
'Down in the plain wooden cabins of the steerage class were 706 immigrants.' I thought that would fit well because 'person versus society' means it shows a struggle between a character and larger social forces, and the only option with a 'person' (in this case people) against a society which I would assume were the rich people and people who could afford to travel in the best conditions and were not struggling like the immigrants?
In the second option, there was no general 'conflict' nor 'people.' In the third option, I guess the 'conflict' could be that the titanic but in general, all the people in the ship were all the same endangered. In the fourth option, there were no people nor any conflict. (I mean unless it was talking about rivalry between the ships or something?)