A.I. Explanation:

Option 1: "Some people who earn too much."

Explanation: This option is incorrect because the text specifies that many of the elderly cannot afford health care, implying that those who earn too much would not be included among those who cannot get proper health care. The phrase 'earn too much' contradicts the context of affordability discussed in the text.

Option 2: "Old people."

Explanation: This option is correct as the text explicitly mentions that a large part of the population, including many of the elderly, cannot afford the expensive private treatment. This directly supports the idea that old people are among those Americans who cannot get proper health care.

Option 3: "Private patients."

Explanation: This option is incorrect because private patients are typically those who can afford the expensive private treatment. The text indicates that the public system was created for those who cannot afford such treatment, thus excluding private patients from the group that cannot get proper health care.

Option 4: "People with insoluble problems."

Explanation: This option is incorrect as it misinterprets the term 'insoluble problems.' The text refers to the health care system having insoluble problems, not the individuals. Therefore, this option does not accurately reflect the group of Americans who cannot get proper health care.