Answer:
B. to state the writer's opinion.
Step-by-step explanation:
A claim can be defined as a statement that is used by a writer to prove, substantiate or support an argument. Thus, a claim is an assertive statement expressed by a writer to prove that an argument is true or real.
Hence, the function of a claim in an argument is simply to state the writer's opinion.
This ultimately implies that, when writers engage in an argument or write an argumentative essay, they make use of a claim to state or express their opinions about the subject matter or topic.