Altruism is the human concern for the wellbeing of others. Altruism has been shown to be motivated more by social bonding, familiarity and identification of belongingness to a group. The notion that altruism may be attributed to empathy or guilt has now been rejected.

Which one of the following is the $\text{CORRECT}$ logical inference based on the information in the above passage?

1. Humans engage in altruism due to guilt but not empathy
2. Humans engage in altruism due to empathy but not guilt
3. Humans engage in altruism due to group identification but not empathy
4. Humans engage in altruism due to empathy but not familiarity