Final answer:
Mandatory spending in the federal budget primarily includes entitlement programs such as Medicare and Medicaid, which fall under health care spending.
Step-by-step explanation:
In the federal budget, mandatory spending is comprised of expenditures that are predetermined by existing laws, rather than being approved annually through the discretionary spending process. The categories of spending included in mandatory spending are typically entitlement programs to which people meeting certain criteria are legally entitled. Among the options given, the correct choice is B. Health care spending, which includes programs such as Medicare and Medicaid, and is considered mandatory as these are entitlement programs secured by law.