Ethos is used in this sentence. Speakers appeal to ethos to show that they are credible and trustworthy. Appeals to ethos emphasize shared values between the speaker and the audience. Speakers build ethos by explaining their credentials or background to show that they are knowledgeable or qualified to speak on a subject.
In this sentence, ethos is used because credibility is established by referring to the professor at Harvard—who has a PhD— whom the speaker consulted.
