Answer:
3. Cause and effect
Step-by-step explanation:
The given paragraph is structured as a cause and effect paragraph. This type of paragraph tells us about why something happens, about what causes certain things (which we refer to as the effect).
In the given example, the cause is the high cost of college. The effect are its consequences. Some students don't go to college because they can't afford it, some work to earn enough money for it, and others begin their careers with large debts because of student loans.
This is why the third option is the correct one.