In the following English vocabulary question, you are given the word "prim". Out of the four alternatives, choose the option which is opposite in meaning, that is, the antonym of the word "prim".

Introduction / Context:
This English vocabulary question tests your understanding of antonyms, that is, words that are opposite in meaning. The given word is "prim", which commonly appears in competitive examinations and reading passages. Knowing the meaning of such adjectives is important because they describe behaviour, attitude and social manners. When you see a question that asks for the opposite meaning, you must first be very clear about the core sense of the original word and then search for an option that expresses the reverse attitude or quality.

Given Data / Assumptions:

• The target word given in the question is "prim".
• The task is to choose the option that is opposite in meaning to "prim".
• The options given are "Particular", "Informal", "Straight", "Nice" and "Proper".
• We assume standard dictionary meanings used in formal written English.
• The question follows the usual rule that exactly one option is fully correct.

Concept / Approach:
The word "prim" is used in English to describe a person who is very formal, easily shocked, and overly proper in behaviour or appearance. A prim person is stiff, serious and may be too concerned about manners and etiquette. The antonym must therefore describe someone or something that is relaxed, casual or not very formal. The general approach is to recall the meaning of "prim", think of its opposite and then compare that idea with each of the given options. Vocabulary questions like this often use everyday descriptive words, so your own reading experience and sense of context are very helpful when you evaluate each choice.

Step-by-Step Solution:
Step 1: Recall that "prim" means very proper, formal, stiff or overly correct in manners. Step 2: Think about the opposite mood or quality. The opposite of being stiff and formal is being relaxed, casual or informal. Step 3: Examine the options. "Informal" directly carries the sense of relaxed or casual, and therefore expresses the opposite of "prim". Step 4: Check the remaining options to confirm that none of them expresses the opposite meaning as clearly as "Informal".

Verification / Alternative check:
To verify the choice, imagine simple sentences. You can say, "She is very prim in her behaviour at parties" to mean she is overly proper and formal. The opposite sense would be, "She is very informal at parties", meaning she is relaxed and casual. These two sentences clearly show opposite social styles. Now test the word "prim" with the other options. A "prim and proper" person is actually described with the word "proper" itself, which suggests that "proper" is close in meaning, not opposite. The same comparison can be made with the remaining options, confirming that "Informal" is the only antonym in the list. This cross check confirms that the selected answer is consistent with common usage.

Why Other Options Are Wrong:
"Particular" means very fussy or precise about details, which is related to carefulness and can even be close to the behaviour of a prim person, so it is not the opposite. "Straight" usually refers to something that is not curved, or to honest and direct behaviour, and does not directly oppose the idea of being prim. "Nice" means pleasant or agreeable and is not the reverse of being formal. "Proper" is often paired with "prim" in the phrase "prim and proper", so it clearly supports a similar meaning rather than the opposite. Therefore, these options cannot be correct antonyms.

Common Pitfalls:
A common mistake in such questions is to choose a word that simply sounds familiar or positive instead of checking the actual semantic relation. Learners sometimes confuse "particular" and "prim" because both may be used for fussy or precise people, and they may incorrectly treat "nice" as a kind of loose opposite of strict behaviour. Another pitfall is not distinguishing between related meanings like neat, tidy, proper and strict. Antonym questions demand careful analysis of nuance rather than quick guessing based on surface impressions. Always pause and test the words in example sentences in your mind.

Final Answer:
The word that is opposite in meaning to "prim" is Informal.