The So-Called "Individual Mandate" in the Affordable Care Act Refers

The so-called "individual mandate" in the Affordable Care Act refers to the requirement that

A) state governments always protect an individual's "right to die."
B) state governments provide the same health care coverage to citizens and undocumented immigrants.
C) state governments expand their Medicaid coverage or lose all of their existing Medicaid funds from the federal government.
D) individuals purchase health care insurance coverage or pay a penalty to the federal government.