A.I. Explanation:

Option 1: "Being able to live longer is a feat for human beings."

Explanation: While the text acknowledges that living longer is a 'feat,' it does not emphasize this as the main opinion of the speaker. Instead, the focus is on the implications of an aging population, particularly the financial burden it creates.

Option 2: "More money will be needed to support the aging population."

Explanation: This option directly aligns with the main idea of the text, which highlights that as the population ages, the costs associated with supporting retirees will become unsustainable. The phrase 'it's expensive' indicates the need for more financial resources to manage this demographic shift.

Option 3: "The aging population is going to grow slowly in the next 4 decades."

Explanation: This statement contradicts the text, which states that the aging population is expected to increase significantly, from one in twelve to one in four by 2050. This indicates a rapid growth, not a slow one.

Option 4: "Medical systems may collapse because of the growing old population."

Explanation: Although the text discusses the financial strain of an aging population, it does not specifically mention the collapse of medical systems. This option introduces a new idea that is not supported by the text.