Choose the one-word substitute that best completes the sentence: "A man with abnormal habits is called _____."

Introduction / Context:
This one-word substitute question checks your knowledge of adjectives used to describe personality traits and behavioural patterns. The phrase "a man with abnormal habits" refers to someone whose behaviour is unusual or unconventional compared to what society expects. Your job is to select the word that most accurately captures this meaning.

Given Data / Assumptions:

- Descriptive phrase: "A man with abnormal habits". - Options: "Eccentric", "Frantic", "Idiotic", "Sulky". - The word should focus on unusual, peculiar behaviour rather than short term emotions. - The tone is descriptive, not necessarily insulting.

Concept / Approach:
"Eccentric" is used in English to describe a person who behaves in odd, unusual, or unconventional ways. An eccentric person may have strange habits, but this term is often neutral or mildly humorous rather than purely negative. The other options refer either to panic, stupidity, or moodiness and do not match the general idea of abnormal or peculiar habits.

Step-by-Step Solution:
Step 1: Break down the phrase "abnormal habits" as behaviour patterns that are different from the usual, often in a noticeable or peculiar way. Step 2: Recall the meaning of "eccentric": a person who is odd or unconventional, often with distinctive habits or tastes. Step 3: Match this to the description given. An eccentric man is precisely one whose habits are unusual or outside normal expectations. Step 4: Examine "frantic". This word describes someone who is wildly excited, anxious, or panicked, often in a short term crisis. It does not describe long term habits. Step 5: Consider "idiotic". This is a strong, rude term meaning very foolish or stupid. It attacks intelligence rather than describing abnormal habits. Step 6: Evaluate "sulky". This describes a person who is gloomy, silent, or resentful, often because they are upset. Again, it is about mood rather than unusual behaviour.

Verification / Alternative check:
Use the options in example sentences: "He is an eccentric old man who collects clocks and talks to his plants" sounds natural and reflects unusual habits. If we say "He is a frantic old man" or "He is a sulky old man", we shift the meaning to emotional state. "Idiotic old man" focuses on intelligence, not habits. Only "eccentric" preserves the sense of ongoing odd behaviour that the question describes.

Why Other Options Are Wrong:
"Frantic" relates to extreme, temporary emotional agitation, not stable patterns of behaviour. "Idiotic" is an offensive synonym for very foolish and does not specifically mean abnormal habits. "Sulky" describes a person who is pouting or silent because of some grievance, which is just one mood, not a broad description of unusual daily habits. Thus, these words do not correctly substitute for the phrase given.

Common Pitfalls:
Because all four options describe people negatively in some way, students may be tempted to choose at random. However, precision matters in one-word substitutes. It is useful to group adjectives by categories: words like "eccentric", "odd", and "quirky" relate to unusual behaviour; "frantic", "agitated", "panicky" relate to emotional states; "sulky", "moody", "morose" relate to moodiness; and "idiotic", "foolish" relate to intelligence. Remembering these groupings makes such questions much easier.

Final Answer:
Eccentric is the correct one-word substitute for "a man with abnormal habits".