What is the function of a claim in an argument? to introduce the topic
to state the writer's opinion
to state a reason for the writer's belief
to give evidence supporting the writer's belief

B. to state the writer's opinion.

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.

for example: in, he, a,from