In personality research aiming to predict future well-being, tends to be more positive years later, and tends to be more negative years later.

The answer is Extraversion;Introversion.
Extrovert tend to be more likely engage in social interractions which improve the probability of having close emotional relationship with other people.
Introverts on the other hand, are tend to avoid social interraction which reduce their probability to have a meaningful relationship and increase the probability of depression.

The correct answer is d. the bottom 40%