Final answer:
The most significant source of federal government revenue is individual income taxes, followed by payroll taxes, with corporate income taxes providing a smaller share.
Step-by-step explanation:
The student has inquired about the main source of the federal government's revenue. Analyzing the information provided, we can establish that the largest portion of federal money, 1.7 trillion dollars, comes from individual income taxes. This is followed by payroll taxes at 1.2 trillion dollars, which are designated for social insurance funding. Corporate income taxes contribute a smaller portion of the federal revenue, totaling 230 billion dollars, and all other sources combined provide 271 billion dollars. Notably, the corporate income tax is the third-largest source, and its share of the federal revenue has decreased over time, from about 4% of GDP in the 1960s to only 1% to 2% of GDP in recent years. Therefore, the correct answer to the student's question is (b) income taxes. Federal tax revenue consists of several different types, with individual income tax being the largest contribution, but it still represents less than half of the total federal tax revenue.