In the following question, one part of the sentence may have a grammatical error. Read the sentence carefully and choose the part that contains an error. If the sentence is free from error, choose "No error". The mother / yearns for / her only child / No error

Introduction:
Some error spotting questions are designed to check if you can recognise a sentence that is already correct. This discourages candidates from inventing mistakes and rewards those who can confidently accept a correct construction. Here, the verb "yearns for" is used to express deep longing, and the sentence appears simple but fully grammatical.

Given Data / Assumptions:
- Sentence: "The mother yearns for her only child."
- Divided parts: "The mother", "yearns for", "her only child", and "No error".
- We assume standard English usage for subject verb agreement and prepositions.

Concept / Approach:
The verb "yearn" means to long deeply or desire strongly. It is often followed by the preposition "for" and then the object of that longing. The subject "The mother" is singular, so the verb should be "yearns" in the present simple tense. The object "her only child" is also correct and complete. Thus, a quick grammar check suggests that the sentence is correct as it stands.

Step-by-Step Solution:
Step 1: Check the subject: "The mother". This is a singular noun phrase.Step 2: Check the verb: "yearns". This is the correct third person singular form of "yearn".Step 3: Check the preposition: "yearns for". The verb "yearn" normally takes "for", so this is correct.Step 4: Check the object: "her only child". This phrase is grammatically sound and clearly expresses what she longs for.Step 5: Combine all parts: "The mother yearns for her only child." The sentence is meaningful and grammatically correct, so no correction is required.

Verification / Alternative check:
Try forming similar sentences to verify the pattern: "He yearns for his homeland", "She yearns for peace", "They yearn for freedom". Each uses "yearn for" followed by the object. The structure in the question matches these examples exactly. There is no issue of tense, agreement, or word order in the given sentence.

Why Other Options Are Wrong:
Option A contains only the subject, which is correct. Option B contains the verb phrase "yearns for", which is both grammatically and idiomatically correct. Option C, "her only child", is the appropriate object of longing, with correct possessive pronoun usage. Since none of these segments is wrong, the option that must be chosen is option D, "No error".

Common Pitfalls:
Because exam candidates often expect every question to contain a mistake, they may try to force a correction, perhaps changing "yearns for" to "yearns after" or altering the tense unnecessarily. This can lead to overcorrection and loss of marks. The important lesson is to trust your grammatical judgment: if a sentence is clear, natural, and follows standard patterns, it may genuinely have no error.

Final Answer:
The sentence is already correct in all its parts, so the right choice is No error.