In the group of three-letter English words LAP, BUT, CAR, SON and HID, each word has its first and third letters interchanged (for example, LAP becomes PAL). After this interchange in every word, which of the given words (if any) becomes a meaningful English word in the new arrangement?

Introduction / Context:
This problem is a simple test of letter position manipulation and vocabulary. You are asked to swap the first and third letters of each three letter word and then decide which resulting words are still meaningful English words. It checks both your ability to carry out positional changes correctly and your recognition of common short words.

Given Data / Assumptions:
• The given three letter words are: LAP, BUT, CAR, SON and HID.
• For each word, the first and third letters are interchanged while the middle letter remains unchanged.
• After this swap, we must see which resulting words are valid English words with standard meanings.

Concept / Approach:
Because all words are exactly three letters long, interchanging the first and third letters simply reverses the outer letters. So ABC becomes CBA. We can therefore apply this operation to each word and then check whether the new form appears as a common English word in everyday usage. There is no need for complex reasoning; careful transformation and basic vocabulary are sufficient.

Step-by-Step Solution:
Step 1: Transform LAP. Swapping first and third letters (L and P) gives P A L, that is "PAL". "PAL" is a common English word meaning friend.Step 2: Transform BUT. Swapping B and T gives T U B, that is "TUB". "TUB" is a familiar word that refers to a large container, often for washing or bathing.Step 3: Transform CAR. Swapping C and R gives R A C, which forms "RAC". This is not a standard common English word in this context.Step 4: Transform SON. Swapping S and N gives N O S, that is "NOS", which is not used as a common English word here.Step 5: Transform HID. Swapping H and D gives D I H, that is "DIH", which again is not a recognised English word.Step 6: Hence, only LAP and BUT become meaningful words after this operation, giving PAL and TUB respectively.

Verification / Alternative check:
You can quickly verify PAL and TUB by recalling their meanings or by mentally placing them in simple sentences such as "He is my pal" and "Fill the tub with water". In contrast, RAC, NOS and DIH do not fit easily into any normal English usage. This confirms our classification of meaningful and non meaningful outputs after the swap.

Why Other Options Are Wrong:
• HID: After swapping, we get DIH, which is not an English word, so HID alone cannot be the correct answer.
• SON: After the swap, SON becomes NOS, which is again not a commonly accepted word.
• Both CAR and LAP: CAR becomes RAC (not meaningful), so including CAR in the correct group would be wrong.
• None of these: This would imply that no word becomes meaningful after swapping, which is false because PAL and TUB are both valid words.

Common Pitfalls:
Sometimes students mistakenly change the order of all three letters instead of swapping only the first and third, or they misread the words during transformation. Others may think of abbreviations or specialised terms to justify RAC or NOS, but aptitude questions generally focus on standard vocabulary. Being strict about the swap rule and checking only well known words keeps your reasoning accurate.

Final Answer:
After interchanging the first and third letters of each word, the words derived from LAP and BUT are meaningful, so the correct choice is Both LAP and BUT.