Final answer:
The subject of this question is Social Studies and it is about understanding the criteria for a person under the age of 70 1/2 who has earned income.
Step-by-step explanation:
The subject of this question falls under Social Studies. This question is about understanding the criteria for a person under the age of 70 1/2 who has earned income. Based on the given information, it seems to be related to topics such as income, employment, and demographic characteristics.