Detailed Instructions: In this task, you're given a passage, further information available on a particular linked term from the statement, and a question. Your job is to generate the answer to the question by using the information provided. If there is no clear answer obtainable, output 'none'.
Q: Passage: At Dark Horse Comics, Grant wrote several limited and ongoing series in the short-lived Dark Horse shared superhero continuity, including the entire two-year run of the series X. His creation Enemy, published by Dark Horse, was optioned and produced as a Fox pilot, but ultimately did not air. He wrote numerous stories for DC Comics in the 1990s and created new versions of Manhunter and the Challengers of the Unknown. He continued to periodically write for Marvel Comics, his last major contribution being X-Man in collaboration with Warren Ellis and Ariel Olivetti. Among his other creator-owned works of the 1990s were the superhero comic Edge, with Gil Kane, published by Malibu Comics/Bravura, and the crime series Damned with Mike Zeck, published by WildStorm.
Link Information: Warren Girard Ellis (born 16 February 1968) Question: Which of the people who Grant collaborated with on X-Man had the longest career?
A:
Answer: Ariel Olivetti