Final answer:
Social Security and Medicare, along with Medicaid payments under the ACA, make it the most difficult for the federal government to control the budget. Therefore, the correct option is a. social security and medicare selected.
Step-by-step explanation:
The type of spending that makes it most difficult for the federal government to control the budget is Social Security and Medicare.
These two programs account for a significant portion of federal government spending and have been steadily growing as a percent of GDP. Social Security and Medicare are considered entitlement programs, meaning that individuals who meet eligibility requirements are legally entitled to benefits.
Additionally, Medicaid payments under the Patient Protection and Affordable Care Act (ACA) also contribute to the difficulty of controlling the budget. Medicaid is funded by both the federal and state governments and provides health insurance to low-income Americans.