The relationship between DIVA and OPERA is "a skilled performer of a particular art form" is to "the art form/performance they are known for". Let's check which pair carries the same performer-to-performance relationship:
Producer and Director both describe people who manage or stage a performance rather than perform in it themselves, and Conductor : Bus is a play on words with no performance sense at all, leaving only the pair that matches performer to performance.
Therefore, the correct answer is Thespian : Play.