The commas are used correctly in the sentence because the underlined element is

If your sentence is " Michael Jordan, the basketball player, won six championships for the Chicago Bulls," then the correct answer is a nonrestrictive phrase.

First of all, the underlined element cannot be a clause because there is no verb there, meaning that it has to be a phrase. Second of all, it cannot be restrictive because its meaning is not essential in this sentence - if you omitted this phrase, the sentence would still keep its meaning because everybody knows who Michael Jordan is. Thus, the correct answer is a nonrestrictive phrase.