The one that strengthened a phenomenon. After 2013's Frozen became the highest-grossing animated film of all time, a genuine cultural phenomenon, the calls for a seemingly inevitable sequel began to grow. Fellow animation studios like Pixar and DreamWorks had been crafting successful follow-ups to their most popular animated films for years, but Disney had long resisted the urge to greenlight theatrical sequels for any of their 21st-century films, namely due to the mistakes of the past. In the 90s and early 00s, Disney had actually been consistently churning out sequels...