What is a biography?

A biography is defined as an account of a person's life written by someone else. This definition emphasizes that biographies are factual representations of an individual's life experiences, achievements, and significant events, crafted by a biographer who conducts research and gathers information from various sources.

In contrast, the other options present different forms of writing. A fictional narrative about a person’s life suggests a blend of fiction with biographical elements, which does not align with the factual nature of biographies. A critical analysis of a historical figure typically involves evaluating their impact, contributions, or significance rather than detailing their life story. Lastly, a collection of personal letters often offers insight into an individual's thoughts and experiences but isn't structured as a comprehensive life account like a biography would be.

Overall, the essence of a biography lies in its intent to provide a detailed, factual narrative woven from someone else's perspective, making the second option the correct answer.