In English vocabulary, choose the single word that can substitute the phrase "A record of one's own life written by oneself".

Introduction / Context:
One-word substitution questions are a popular feature of English vocabulary sections in competitive exams. They test whether you can match a descriptive phrase with a precise term. The phrase in this question, "A record of one's own life written by oneself", refers to a specific kind of life story, and the correct technical term is vital for clear communication in English.

Given Data / Assumptions:

• Phrase: "A record of one's own life written by oneself".
• Options: History, Biography, Bibliography, Autobiography.
• The key clue is that the life account is written by the person whose life is being described.
• We assume standard dictionary meanings for all the options.

Concept / Approach:
The important distinction lies between "biography" and "autobiography". A "biography" is a life story written by someone else, whereas an "autobiography" is written by the person themselves. "History" deals with events of the past, usually of nations or subjects, and "bibliography" is a list of books or references. Thus, the correct term must indicate both the life story and the fact that the author and the subject are the same person.

Step-by-Step Solution:
Step 1: Identify the core elements: it is a "record of one's own life" and it is "written by oneself". Step 2: Recall that "biography" means the life story of a person written by another person. This does not satisfy the "by oneself" part. Step 3: Recall that "autobiography" comes from "auto" (self) and "biography" (life story), meaning a self-written life story. Step 4: Rule out "history" because it generally covers broader events, not just one person's self-record. Step 5: Rule out "bibliography" because it refers to a list of books or writings, usually at the end of research work. Step 6: Conclude that "Autobiography" exactly matches the entire descriptive phrase in the question.

Verification / Alternative check:
Consider real-world examples: "The Story of My Experiments with Truth" by Mahatma Gandhi is an autobiography because Gandhi wrote about his own life. In contrast, a book about Gandhi written by another author is a biography. Dictionaries clearly define "autobiography" as "an account of a person's life written by that person." This directly corresponds to the phrase given in the question, confirming that the correct option is "Autobiography".

Why Other Options Are Wrong:

• History: Deals with past events, periods, or the development of a country or subject, not specifically self-written life accounts.
• Biography: A life story written by someone other than the person whose life is described, so it fails the "written by oneself" condition.
• Bibliography: A systematic list of books and articles used in research or on a topic, not a narrative of a person's life.

Common Pitfalls:
Many students confuse "biography" and "autobiography" because both deal with life stories. The key is to focus on who writes the account. The prefix "auto" means "self". Remembering this small root meaning will help you quickly choose the correct word in one-word substitution questions. Also, do not be distracted by similar-sounding words like "bibliography", which are common in academic contexts but have a completely different meaning.

Final Answer:
The correct one-word substitution is Autobiography.