(a)

JEFF: I feel tht its the right time to go steady as we are mature enough to know whats right and whats wrong.
Sean: No, I don't think it is the right time. We are not mature enough to go steady as it leads us to fantasizing about the person.

(b)

JEFF: It is mostly true. At this age, sex is not in our mind, unless our sex drive is excessively high.
Sean: It is true. Sex is just a desire.