However, can someone explain "E" to me? Still struggling a little.
1. If people feel happy, those people require to be needed.
2. Most people in modern society can have this needed feeling only from the sphere of family and friendship.
* It means that " some " of people in modern society can have this needed feeling " not " only from the sphere of family and friendship.
Inference:
Most people in modern society as a group belongs to the " people ", then the other group also belongs to the " people " must be few people in modern society.
So, If most people in modern society can have an emotion, its requires that they must gain this emotion only from a group.
Then it must true that if few people in modern society can also have that emotion, it's requires that " they must gain this emotion not necessary only from that group. Which is to say, they can still have the emotion from that group, but it also means that it's ok for them to retrieve that emotion outside of that group.
So, regardless almost everyone knows that their job could be done by anyone, few of people in modern society still can feel happy by feeling needed from either outside the sphere of family and friendship or both inside and outside the sphere of family and friendship.
If that's the case, then we know the number of people in modern society who can only feel needed from only the sphere of family and friendship for the sake of being happy must larger than the number of people who can do such outside the sphere of family and friendship.
That is basically what E says.
* my humble 2 cents here, its not simply just a inference question, since it firstly requires you to " infer " for any must-be-true propositions, and then asks you to identify " necessary assumption " from those proposition matching the answers.