The age 30 transition can be a difficult period because
a. divorces are common.
b. shift in the direction for future developments.
c. make a place for themselves in the adult world.
d. all of the above

So, I would say that the best answer is
c. make a place for themselves in the adult world.

while the other might also hold, is it the fact that until 29 we still tend to feel as "on the way": as in; we are still young and only preparing to be part of the adult would.

while at 30 people are more expected to be settled down and have a place (family, stable job, etc).

Afine-grained igneous rock forms as a result of slow cooling.

Ithink it would be choice b (county). hope this you!