Select the synonym of the word "cantankerous", which describes a person who is difficult and always ready to argue.

Introduction / Context:
Synonym questions test your depth of vocabulary by asking you to match a given word with another of similar meaning. Cantankerous is an adjective often used to describe people who are difficult to deal with, bad tempered, and quick to argue. Such words commonly appear in reading comprehension passages or character descriptions in literature, so recognising them is useful for both exams and general understanding.

Given Data / Assumptions:

• Target word: cantankerous.
• Four options: humorous, quarrelsome, remorseful, dullness.
• The word is used primarily to characterise a person's temper or behaviour.
• We need to select the closest meaning, not an opposite or unrelated word.

Concept / Approach:
Cantankerous describes someone who is always complaining, easily annoyed, and eager to argue or fight. The closest everyday word for this quality is quarrelsome, which means inclined to quarrel or argue frequently. The other options describe completely different emotional states: humorous relates to fun, remorseful to regret, and dullness to lack of interest or brightness. Therefore, quarrelsome is the only synonym that fits the semantic field of cantankerous.

Step-by-Step Solution:
Step 1: Recall the approximate meaning of cantankerous as bad tempered and argumentative. Step 2: Examine each option and link it to its core meaning. Step 3: Identify quarrelsome as meaning inclined to quarrel or argue, which is very close to cantankerous. Step 4: Notice that humorous suggests a playful or funny nature and is the opposite of sour temperament. Step 5: Recognise remorseful and dullness as unrelated to the idea of being argumentative and therefore reject them.

Verification / Alternative check:
Try using the words in similar sentences. For example, He is a cantankerous old man fits well with He is a quarrelsome old man. Both suggest a person who likes to argue. Replacing cantankerous with humorous or remorseful would completely change the picture. Similarly, saying He is a dullness old man is not even grammatically acceptable. These comparisons confirm that quarrelsome is the correct synonym for cantankerous in this context.

Why Other Options Are Wrong:
Humorous refers to someone who has a sense of humour and likes to make others laugh, which is almost the opposite of the irritable and argumentative tone of cantankerous.

Remorseful describes a person filled with regret or guilt about something wrong they have done, which has nothing to do with the love of quarrelling.

Dullness is a noun meaning lack of interest, excitement, or brightness and is not even the same part of speech as cantankerous, which is an adjective.

Common Pitfalls:
Some learners may confuse cantankerous with melancholic or sad, because both can describe negative emotional states, but the core difference is important: cantankerous people argue and complain, while sad people may remain quiet. Building word families, such as cantankerous, quarrelsome, irritable, and grumpy, helps reinforce meaning clusters and improves synonym recognition.

Final Answer:
The synonym of cantankerous in the given options is Quarrelsome.