In the following grammar question on error spotting, identify the part of the sentence that contains an error: The task of (A) writing a autobiography (B) is a difficult one (C).

Introduction / Context:
Error spotting questions are designed to test a learner grasp of English grammar and usage. The sentence is divided into labelled parts, and the candidate has to find the segment containing a mistake. In this question, the sentence reads The task of writing a autobiography is a difficult one. The structure is fairly simple, so the main focus is likely on articles, noun forms, or prepositional usage. Recognising small yet important errors such as incorrect use of a and an is essential for accurate written and spoken English.

Given Data / Assumptions:

• Sentence: The task of (A) writing a autobiography (B) is a difficult one (C).
• Option D corresponds to No error.
• We need to find the segment that contains a clear grammatical or usage error.
• Standard rules of English articles before vowel and consonant sounds apply.

Concept / Approach:
The sentence structure The task of writing an autobiography is a difficult one is otherwise correct in terms of verb agreement and word order. The error lies in part B, where the phrase a autobiography appears. In English, the indefinite article a is used before words beginning with a consonant sound, and an is used before words beginning with a vowel sound. The word autobiography begins with a vowel sound, so the correct phrase is an autobiography. Identifying this basic rule of article usage immediately reveals the error segment.

Step-by-Step Solution:

Verification / Alternative check:
To verify, say the corrected sentence aloud: The task of writing an autobiography is a difficult one. It sounds natural and adheres to standard English rules. If we retain a autobiography, the sentence feels awkward and clearly conflicts with the widely taught rule for article usage. There are no other issues in the sentence. The phrase the task of writing is grammatically correct, and the clause is a difficult one correctly uses the singular verb and predicate complement. Therefore, the only error is in part B, the article before autobiography.

Why Other Options Are Wrong:

• Option A (The task of) is correct because the phrase introduces the subject of the sentence properly.
• Option C (is a difficult one) is grammatically accurate and matches the singular subject task.
• Option D (No error) is incorrect because we have clearly identified an error in part B.

Common Pitfalls:
Many candidates read quickly and miss small article errors, especially when they are more focused on verbs and tenses. Another pitfall is confusion between spelling and sound; some learners mechanically look at the letter rather than the pronunciation. The key is to remember that the choice between a and an depends on the sound that immediately follows, not just the first letter. Words like university, which start with a consonant sound, take a, whereas autobiography, which begins with a vowel sound, correctly takes an. Practising such examples can greatly reduce errors in exam conditions.

Final Answer:
B