Final answer:
Harman and Ising joined Metro-Goldwyn-Mayer (MGM) when seeking a distributor for their cartoons. They played a key role in developing MGM's animation department after having worked on Warner Bros.' Looney Tunes and Merrie Melodies series.
Step-by-step explanation:
When Harman and Ising were looking for a distributor for their new cartoon series, they joined forces with Metro-Goldwyn-Mayer (MGM). Hugh Harman and Rudolf Ising were animators who had worked at Warner Bros. on the Looney Tunes and Merrie Melodies series before seeking a distributor for their own series of cartoons. After a brief stint with Metro-Goldwyn-Mayer, they contributed significantly to the development of MGM's animation department.