Which of the following words is the best antonym (opposite in meaning) of the adjective sober?

Introduction / Context:
This vocabulary question checks your understanding of the adjective sober and asks you to choose the best antonym, that is, the word with the opposite meaning. Sober is commonly used in two senses: not drunk and calm or serious in manner. The options mix definitions and near synonyms, so you need to think about meaning carefully rather than simply matching a familiar phrase.

Given Data / Assumptions:

• The word in question is the adjective sober.
• Option A not affected by alcohol is actually a definition of sober, not its opposite.
• Options B sensible and C serious are also close in meaning to sober in the sense of calm and thoughtful.
• Option D emotional suggests strong, often uncontrolled feelings, which contrasts with a sober mood.

Concept / Approach:
To find an antonym, we first recall the core meanings of sober. In many English exams, sober in a figurative context means serious, reasonable, and not overly emotional or playful. A sober assessment, for example, is calm and balanced. The opposite idea is behaviour or attitude that is ruled by strong feelings rather than calm judgment. Therefore, a word that points to being dominated by emotion is a suitable antonym. Emotional captures this contrast better than any other option given, because it suggests that feelings are prominent and may overshadow calm reason.

Step-by-Step Solution:
Step 1: Write down the main senses of sober: not drunk and calm or serious in character or mood.Step 2: Examine option A, not affected by alcohol. This matches the literal meaning of sober rather than opposing it, so it cannot be the antonym.Step 3: Examine option B, sensible. A sensible person is thoughtful and practical, which is close to the figurative meaning of sober, so this is a synonym, not an antonym.Step 4: Examine option C, serious. This is again a near synonym of sober when we talk about a sober expression or sober mood.Step 5: Examine option D, emotional. This suggests a tendency to show strong feelings and lose some calmness. It stands in clear contrast to sober in the sense of restrained and serious, so it is the best antonym provided.

Verification / Alternative check:
We can test the options in example sentences. If we say a sober discussion, we imagine a calm, serious discussion. Replacing sober with sensible or serious keeps a similar tone. However, an emotional discussion brings to mind raised voices, tears, or excitement, the opposite of calm seriousness. In another example, a sober reaction to bad news implies control and restraint, while an emotional reaction suggests visible distress. These comparisons confirm that emotional is the strongest opposite among the choices.

Why Other Options Are Wrong:
Option A not affected by alcohol directly defines sober rather than giving an opposite. Option B sensible and option C serious both describe attitudes that align with the figurative meaning of sober. None of them introduce contrast or opposition, so they cannot serve as antonyms in this question. Only emotional clearly opposes the calm, controlled quality conveyed by sober.

Common Pitfalls:
A frequent mistake is to think only of the alcohol related meaning and look for a word like drunk, which is not present here. Another pitfall is to choose a familiar definition (option A) without noticing that the question asks for an antonym. Always read the stem carefully and decide whether the exam is testing synonym, antonym, or definition before selecting your answer.

Final Answer:
The best antonym of sober in this context is Emotional, because it contrasts with the calm and serious quality of a sober attitude.