Final answer:
The correct answer is c. birth; achievement. Being in the upper-upper class is usually the result of birth, while being in the lower-upper class is more a matter of achievement.
Step-by-step explanation:
The correct answer is c. birth; achievement. Being in the upper-upper class is usually the result of birth, meaning that individuals are born into wealthy families and inherit their wealth and status. On the other hand, being in the lower-upper class is more a matter of achievement, where individuals have worked hard and achieved success, typically through business ventures or entrepreneurship.