Definition: In this task, you're expected to write answers to questions involving multiple references to the same entity. The answer to the question should be unambiguous and a phrase in the paragraph. Most questions can have only one correct answer.
Input: Passage: The unnamed Narrator is an automobile recall specialist who is unfulfilled by his job and possessions, and has developed severe insomnia. He finds catharsis by posing as a sufferer of testicular cancer and other afflictions in support groups, remedying his insomnia. His bliss is disturbed by another impostor, Marla Singer, whose presence reminds him he is attending these groups dishonestly. The two agree to split which groups they attend, but not before they exchange contact details on the premise of switching groups at short notice.
On a flight home from a business trip, the Narrator meets and interacts with soap salesman Tyler Durden. The Narrator returns home to find that his apartment has been destroyed by an explosion. Deciding against asking Marla for help, he calls Tyler, and they meet at a bar. Tyler says the Narrator is beholden to consumerism. In the parking lot, he asks the Narrator to hit him, and they begin a fistfight.
The Narrator is invited to move into Tyler's home: a large, dilapidated house in an industrial area. They have further fights outside the bar, which attract growing crowds of men. The fights move to the bar's basement where the men form Fight Club, which routinely meets for the men to fight recreationally.
Marla overdoses on pills and telephones the Narrator for help; he ignores her, but Tyler picks up the phone and goes to her apartment to save her. Tyler and Marla get sexually involved, and Tyler warns the Narrator never to talk to Marla about him. The Narrator blackmails his boss and quits his job. 
Question: What is the last name of the person who saves Marla?

Durden.