In this one word substitution question, select the correct English word that describes "a person who completely abstains from alcohol" and does not drink alcoholic beverages at all.

Introduction / Context:
This question is from the one word substitution section of English vocabulary. You are given a descriptive phrase and asked to choose the single word that accurately represents the idea. Here, the description is "a person who completely abstains from alcohol". Such questions are important in exams because they test the precision of your vocabulary and your familiarity with common formal terms.

Given Data / Assumptions:

• The description is "a person who completely abstains from alcohol".
• Four options are presented as possible substitutes.
• You must choose the word that correctly refers to someone who never drinks alcoholic beverages.
• The correct word will be a standard dictionary term used in social and health related discussions.

Concept / Approach:
One word substitution tasks require you to capture the core concept expressed in many words and match it with a concise, standard term. The key phrase here is "completely abstains from alcohol". In English, the word used for such a person is "teetotaller" in British spelling, or "teetotaler" in American spelling. It refers specifically to someone who has taken a pledge of total abstinence from alcohol and does not drink at all.

Step-by-Step Solution:
Step 1: Identify the main idea in the description: total avoidance of alcohol.Step 2: Recall words commonly connected with alcohol use, such as "drunkard", "alcoholic", and "teetotaller".Step 3: Observe that "drunkard" and "alcoholic" describe people who consume alcohol excessively, not those who avoid it.Step 4: Remember that "teetotaller" explicitly describes a person who refuses to drink any alcoholic beverage.Step 5: Confirm that "Teetotaller" fits the full definition and therefore is the correct choice.

Verification / Alternative check:
You can verify your choice by placing each option into a sample sentence: "He is a ______ by conviction." If you say "He is a teetotaller by conviction", the sentence clearly means he does not drink alcohol. If you try "drunkard" or "alcoholic" in this sentence, the meaning changes to someone who drinks too much, which is the opposite of the given description. This confirms that "Teetotaller" is the correct word.

Why Other Options Are Wrong:
Option B, "Drunkard", refers to a person who frequently drinks alcohol and is often drunk, the direct opposite of abstaining. Option C, "Alcoholic", is used for someone who is addicted to alcohol, usually needing professional help. Option D, "Imposter", is someone who pretends to be another person or fakes an identity and has nothing to do with alcohol consumption or abstinence.

Common Pitfalls:
A common mistake is to pick a word that seems familiar or connected to alcohol, without checking whether it refers to use or abstinence. Another pitfall is confusion over spelling, since "teetotaller" may look unusual. In exam conditions, focus on the exact meaning of the root idea "total abstinence" and connect it with the word that reflects this abstinence, not any word that simply belongs to the alcohol theme.

Final Answer:
The correct answer is Teetotaller, because this word is used in English to describe a person who completely abstains from alcohol and does not consume alcoholic drinks at all.