Complex sentence: This season was produced along with season 18 in 2013, and is the fourth and final season to be animated by 9 Story Media Group, as seasons 20 and 21 of Arthur will be animated by Oasis Animation.
Split into simpler sentences: This season was produced along with season 18 in 2013. This is the fourth and final season to be animated by 9 Story Media Group, as seasons 20 and 21 of Arthur will be animated by Oasis Animation.