Which of the Following Are the Two Most Important Sources

Which of the following are the two most important sources of contract law?

A) Case law and the Restatement of Law.
B) Case law and the Uniform Commercial Code.
C) The Uniform Commercial Code and the Convention on Contracts for International Sales of Goods.
D) Case law and the Convention on Contracts for International Sales of Goods.
E) The Convention on Contracts for International Sales of Goods and the Restatement of the Law, Contracts.