Quiz: Writing for business — is, are

Which is correct?

Jeff Bezos, as well as Bill Gates and Steve Jobs, _____ going to be at the conference.
a. is
b. are

Correct answer: a

Explanation

Even though there are three speakers in the sentence, the modifying phrase contained within commas is not part of the grammatical subject. Jeff Bezos is the subject of the sentence. A singular subject requires a singular verb.