Given a factoid/trivia type question, generate the topic of the question. The topic is the entity the question talks about.

Input: Consider Input: What's missing: Magnum Force, The Enforcer, Sudden Impact, and The Dead Pool?

Output: sudden impact


Input: Consider Input: Which is the only Avril Lavigne song to have reached No.1 in the US Billboard Chart?

Output: avril lavigne


Input: Consider Input: Which evolutionary biologist wrote The Ancestor's Tale in 2004?


Output: the ancestor's tale