The researcher is analyzing a problem involving the sale of goods on credit in state A. The following authority has been located concerning the problem:

1. State A's Uniform Commercial Code Act
2. State A's Consumer Credit Act
3. State B's Uniform Commercial Code Act
4. A federal statute - Consumer Credit Act
5. Iron v. Supply Co. - a decision of the highest court in state A.
6. Milk v. Best Buy Inc. - a decision of the highest court in state B
7. Control Co. v. Martin - a decision of an intermediary court of appeals in state A
8. Lesley v. Karl Co.-a decision of a trial court in state A
9. Irene v. City Co. - a federal case involving the federal Consumer Credit Act
10. Regulations adopted by state A's Corporation Commission that apply to consumer credit and the sale of goods.
11. Restatements of the law defining sales, consumer credit, and other terms related to the problem.
12. An ALR reference that directly addresses the issues in the case.

Assume that all the cases are on point, that is, they are sufficiently similar to the facts and issues involved in the problem to apply as precedent.

b. Why authority can be mandatory authority? Why?

What would be required for any of the sources to be mandatory authority?