Question

which sentence contains a correctly punctuated nonrestrictive modifier?
jake, who is twenty-seven, is studying to be a yoga teacher.
jake who is, twenty-seven, is studying to be a yoga teacher.
jake who is twenty-seven is, studying to be, a yoga teacher.
jake, who is twenty-seven is, studying to be a yoga teacher.

Explanation:

A nonrestrictive modifier adds extra, non-essential information to a sentence and must be set off by commas on both sides. The modifier "who is twenty-seven" is nonessential here, so it needs commas before "who" and after "twenty-seven".

Answer:

Jake, who is twenty-seven, is studying to be a yoga teacher.