Answer: DECLINING BIRTHRATES
Explanation: Declining birthrate can be said to be a reduction or diminution of the ratio of total live births to total population for a specific community or nation in a specified period; often expressed in births per thousand per year.
According to the Question, the best represented scenario is the declining birthrate. This is because every other situation occuring here (hardly have any responsibilities; leaving them with more than enough money to spend on luxury goods) is as a result of them not giving birth to more than one child.