Answer: A. An expert's opinion.
Explanation: A persuasive essay has the objective of convincing the readers of a perspective or point of view (expressed as the claim of the essay) in a controversial topic. When writing a persuasive essay it is extremely important to uses reliable sources to support the claim, because this gives the audience trust and helps to refute a possible counterclaim. From the given options the one that is a valid evidence in a persuasive essay is an expert's opinion.
