How are legal rulings made by American judges an example of common law?

How are legal rulings made by American judges an example of common law?
 
  a. Their rulings are based on both precedent and written statutes.
  b. Their decisions are narrowly confined to a specific question of law.
  c. Their decisions are backed by a reasoned justification for the ruling.
  d. Their rulings apply to a broad class of cases rather than just a single dispute.

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Which statement explains why a candidate for office in the United States would find the issue of abortion politically challenging?
 
  a. Supreme Court rulings protect abortion rights from political meddling.
  b. Catholics and Protestant fundamentalists are highly influential interest groups.
  c. Many Americans base their vote solely on a candidate's position on social issues.
  d. American voters who support abortion rights are also likely to oppose same-sex marriage.

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Which of these is the most significant cause for democratic failure?
 
  a. religious diversity
  b. lack of a middle class
  c. a large number of interest groups
  d. an elite-based educational system