Common law (also called case law or precedent) is a source of law that is derived from:

a. a single document that contains all laws.
b. court decisions.
c. popular culture.
d. federal rules and regulations.

The answer is B. Court decisions.

Explanation:

Common law refers to a law that is derived from courts' judicial decisions as well as other similar tribunals. The most important characteristic of common law is that it emerges as a precedent.

Common law is usually utilized when the parties disagree about the establishment of a specific law. In this case, a common-law court reviews the decisions that were considered in the past by relevant courts and summarizes the different principles related to those cases to apply them to the current facts.  

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