Answer:
a. course of dealing
Step-by-step explanation:
Under UCC which is an acronym for Uniform Commercial Code, "a course of dealing" as explained in the subsection 1-303(b) is a term that describes or explains the sequence of conduct concerning previous transactions between the parties to a particular transaction that is fairly to be regarded as establishing a common basis of understanding for interpreting their expressions and other conduct.
It is often used to explain or further give credence to written contract, such that, in a court of law, it is used to assess the position of parties to the the contract, this tends to understand what the parties to contract seek to achieve, based on their previous dealings on transaction.