Explanation:

- "Meat" and "Vegetarian" are opposites in terms of diet choices. Vegetarians do not consume meat.

- "Alcohol" and "Teetotaller" are similarly related as opposites. A teetotaller abstains from consuming alcohol.

- Water is a neutral beverage choice, unrelated to abstaining from alcohol.

- Smoker refers to someone who smokes, unrelated to alcohol consumption in the context of abstinence.

- Dietician is a professional expert who advises on diet, without direct relevance to alcohol consumption habits.

- Teetotaller is the correct answer, as it represents someone who does not consume alcohol, similar to how a vegetarian avoids meat.