In the following question, out of the four alternatives, select the word that is opposite in meaning to the given word: Sullen.

Introduction / Context:
This vocabulary item asks for the antonym, or opposite, of the word "sullen". Many examinations test emotional adjectives and expect learners to distinguish between similar shades of mood. Understanding what "sullen" means and then choosing a word that expresses the opposite emotional state is the key to answering correctly.

Given Data / Assumptions:

• Target word: "Sullen".
• Options: "Glum", "Silent", "Crabby", "Agreeable".
• "Sullen" usually describes someone who is bad tempered, gloomy, and unsociable.

Concept / Approach:
"Sullen" refers to a mood that is dark, resentful, or quietly angry. A sullen person is often unsmiling, unfriendly, and unwilling to talk. To find an antonym, we need a word that suggests friendliness, pleasantness, or readiness to cooperate. Among the options, "agreeable" best captures a cheerful, pleasant, and cooperative attitude, which is the opposite of sullen behaviour. The other options either share a similar gloomy meaning or are only loosely related.

Step-by-Step Solution:
Step 1: Recall that "sullen" describes someone who is silently angry, gloomy, or sulky. Step 2: Examine "Glum". This means sad or depressed, which is very close to "sullen", so it is a synonym, not an antonym. Step 3: Examine "Silent". While sullen people can be silent, silence alone does not capture the mood of bad temper, so this is not a direct opposite. Step 4: Examine "Crabby". This means easily annoyed or irritable, which again resembles the bad temper associated with being sullen. Step 5: Examine "Agreeable". This means pleasant, easy to get along with, and willing to agree, which is the emotional opposite of sullen mood. Step 6: Conclude that "Agreeable" is the correct antonym.

Verification / Alternative check:
Imagine two people: one sits in a corner, frowning, refusing to talk and looking gloomy; this is a sullen person. Another smiles, responds politely, and cooperates with others; this is an agreeable person. Clearly, these two states of mind are opposite. In contrast, glum and crabby both describe negative moods that are similar to sullen, not opposite. Therefore, the choice of "agreeable" is confirmed.

Why Other Options Are Wrong:

• Glum: Means sad or depressed, which supports the gloomy aspect of sullen, so it is similar, not opposite.
• Silent: Only describes the absence of speech; a person can be silent for many reasons and not all silent people are sullen.
• Crabby: Means irritable and easily annoyed, which is again close to sullen temperament.
• Agreeable: Correctly describes a pleasant and cooperative personality, opposite to the sulky, resentful nature of a sullen person.

Common Pitfalls:
Students may rush and pick "silent" because they associate sullen behaviour with not talking, but this is focusing on only one outward sign instead of the overall mood. Others may be distracted by words that simply sound familiar. The best strategy is to think of a full character description: a sullen person is gloomy and withdrawn, so the opposite must be cheerful and cooperative, which is best captured by "agreeable".

Final Answer:
The word opposite in meaning to "sullen" is Agreeable.