In the 1980s, states raised the minimum drinking age to 21. What role did the federal government play in bringing this about?

a. Congress required states to raise the drinking age as a condition for receiving federal highway funding.
b. The president issued an executive order requiring states to raise the drinking age.
c. The Supreme Court issued a decision invalidating state laws that allowed drinking by people under 21.
d. Congress made raising the drinking age an eligibility requirement for a competitive grant program.

Answer: a