In this sentence improvement question, choose the correct idiomatic expression. Original sentence: The cities are bursting on the seams with people.

Introduction / Context:
This question tests your knowledge of a common English idiom used to describe overcrowded places. When a city, room, or container is extremely full, we say it is bursting at the seams. The original sentence uses an incorrect preposition and article, which makes the expression non standard. You need to select the option that restores the idiom to its correct form.

Given Data / Assumptions:

• The sentence describes cities that are very crowded with people.
• The phrase given is bursting on the seams, which sounds wrong.
• Options include different combinations of on, at, and the.
• We assume the test is based on standard idiomatic English usage.

Concept / Approach:
The fixed expression is bursting at the seams, not on the seams or at seams. It originally refers to clothing that is so tight that the seams might break, and later it extended to describe any place that is overcrowded. Idioms often have fixed prepositions and articles. Changing them usually makes the expression incorrect or unnatural. Therefore, we must choose the option that exactly matches the established idiom with at and the.

Step-by-Step Solution:
Step 1: Identify that the sentence aims to use an idiom about being extremely full or crowded. Step 2: Recall that the correct idiom is bursting at the seams. Step 3: Compare each option with the known idiom. Option c, bursting at the seams, matches exactly. Step 4: Note that option a, bursting on seams, replaces at with on and omits the article, which is incorrect. Step 5: Note that option b, bursting at seams, misses the article the, which also makes it non standard. Step 6: Observe that No improvement cannot be correct because the original uses on the seams instead of at the seams. Step 7: Select option c as it reproduces the idiom accurately.

Verification / Alternative check:
You can verify the expression by recalling familiar usage. Newspapers, stories, and conversations often contain sentences like The stadium was bursting at the seams or The train was bursting at the seams during rush hour. You will rarely, if ever, see bursting on the seams in standard English writing. This confirms that at the seams is the correct and idiomatic phrase.

Why Other Options Are Wrong:
Bursting on seams is wrong because on is not the standard preposition for this idiom and the missing article the makes it incomplete. Bursting at seams is closer but still incorrect because idioms usually require specific articles, and here the is part of the fixed phrase. No improvement is wrong because it accepts the non idiomatic version from the original sentence.

Common Pitfalls:
Learners sometimes think prepositions are interchangeable and accept bursting on the seams because it seems logical. However, with idioms, logic is less important than established usage. It is important to memorise common expressions exactly as native speakers use them. Practising such idioms will help in error spotting and sentence improvement sections of competitive exams.

Final Answer:
The correct idiomatic expression is The cities are bursting at the seams with people.