Question: In 1991, The Ren & Stimpy Show was one of Nickelodeon's original three Nicktoons series along with Doug and which other show?
Sentence (from "The Ren &amp; Stimpy Show"): The series follows the adventures of title characters Ren, an emotionally unstable chihuahua, and Stimpy, a good-natured, dimwitted cat.
Relevant evidence: No