In the following question, a sentence is divided into four parts. Identify the part that contains a grammatical error, or select 4 if there is no error: The reason why he failed (1)/ to attend the meeting (2)/ with a complete presentation (3)/ was because he was unwell. (4)

Introduction / Context:
This error-spotting question examines your understanding of redundancy in English expressions, especially in sentences stating reasons. The sentence explains why someone failed to attend a meeting with a complete presentation. You must identify which numbered part has a grammatical or idiomatic problem, or decide that the sentence has no error at all.

Given Data / Assumptions:
- Sentence segments:
- (1) The reason why he failed
- (2) to attend the meeting
- (3) with a complete presentation
- (4) was because he was unwell.
- The sentence is intended to express one clear cause for his failure.
- The structure should be concise and free from unnecessary repetition.

Concept / Approach:
The key concept is avoiding redundant expressions of reason. The phrase the reason why already introduces a cause, so following it with because creates a double expression of the same idea. Standard, formal English prefers either The reason is that... or He failed because..., but not The reason is because.... In exam questions, this redundancy is treated as incorrect usage and is a common target in error-spotting exercises.

Step-by-Step Solution:
Step 1: Read part (1): The reason why he failed. This is an acceptable way to introduce the cause of his failure.Step 2: Part (2): to attend the meeting correctly continues the infinitive phrase and explains what he failed to do.Step 3: Part (3): with a complete presentation adds additional detail and is grammatically fine.Step 4: Part (4): was because he was unwell combines was with because, following the earlier phrase the reason why and creating redundancy.Step 5: The corrected version should read: The reason why he failed to attend the meeting with a complete presentation was that he was unwell.Step 6: Therefore, the error lies in part (4).

Verification / Alternative check:
We can compare correct patterns: The reason for his failure was that he was unwell and He failed to attend the meeting with a complete presentation because he was unwell are both standard. However, The reason... was because he was unwell repeats the notion of cause twice. Grammar books and exam keys generally mark reason... because structures as incorrect. No grammar or usage issues appear in parts (1), (2) or (3), confirming that part (4) is the only erroneous segment.

Why Other Options Are Wrong:
- Part (1) The reason why he failed is acceptable as a lead-in to the cause.
- Part (2) to attend the meeting is grammatically correct.
- Part (3) with a complete presentation is correctly formed and fits the context.
- Since part (4) contains the redundancy, No error is not an acceptable answer.

Common Pitfalls:
A frequent mistake is to overlook redundancy because the structure sounds familiar in casual speech. Many people say the reason is because in everyday conversation, but exams expect concise, non-repetitive constructions. Another pitfall is focusing only on tense or subject-verb agreement and missing idiomatic issues. Always review the sentence for unnecessary repetition, particularly in expressions of cause such as reason, because, due to and since.

Final Answer:
The incorrect segment is part 4. The phrase was because should be replaced with was that, making the correct sentence: The reason why he failed to attend the meeting with a complete presentation was that he was unwell.