In the following sentence, identify the part that contains an error: Was it him, that the teacher (A) / punished for not submitting (B) / his project on time (C) / No error (D).

Introduction / Context:
Error spotting questions test your ability to notice subtle grammatical mistakes in English sentences. This sentence describes a situation where a teacher punished a particular student for not submitting a project on time. The error lies in pronoun case and the structure of the relative clause, both of which are common points of confusion in exams.

Given Data / Assumptions:

• The sentence is divided into parts: Was it him, that the teacher (A) / punished for not submitting (B) / his project on time (C) / No error (D).
• Part A: Was it him, that the teacher.
• Part B: punished for not submitting.
• Part C: his project on time.
• We must find which part contains the error, assuming only one part is marked as wrong.

Concept / Approach:
There are two issues hidden in part A. The verb was, when followed by a pronoun complement, normally takes the subject form he, not the object form him, in formal English, especially in constructions like It was he who. Also, after a personal reference, the relative pronoun should be who or whom, not that, when referring to a person. So a fully formal version would be Was it he whom the teacher punished. However, exam questions typically focus on one main point, here the incorrect usage of him after was it in a subject complement position.

Step-by-Step Solution:
Step 1: Read the sentence as given: Was it him, that the teacher punished for not submitting his project on time. Step 2: Focus on the initial clause Was it him. In standard formal grammar, the structure with a pronoun complement is It was he, It was she, It was they and so on. Step 3: Recognise that him is the object form and he is the subject form required after the linking verb was in this structure. Step 4: Check parts B and C: punished for not submitting and his project on time. Both are grammatically correct and clearly describe why the punishment occurred. Step 5: Conclude that the error is in part A, which should read Was it he whom the teacher punished for not submitting his project on time.

Verification / Alternative check:
To verify, rewrite the sentence in a slightly different way: The teacher punished him for not submitting his project on time. Here him is correct as an object. But when we move the pronoun after was it and make it a complement, the more formal version is Was it he. Grammar books often illustrate this with examples like It was he who called you. This shows that the exam expects recognition of the subject pronoun he after was it in this structure.

Why Other Options Are Wrong:
Part B has no error because punished for not submitting correctly explains the reason for punishment and uses the gerund submitting properly. Part C is also correct because his project on time is a grammatical object phrase with an appropriate time expression. Part D, No error, is wrong because we have already identified a clear grammatical issue in part A, so the sentence cannot be error free.

Common Pitfalls:
Everyday spoken English sometimes uses It was him or It was her, so students may think this is acceptable in exam English. However, competitive exams typically follow formal grammar standards. Another pitfall is focusing too much on the relative pronoun that and missing the more fundamental case error in him. When checking for errors, always examine pronoun case after linking verbs like is, was, are, especially in structures beginning with It was.

Final Answer:
The error is in part A; the formal structure should be Was it he whom the teacher punished for not submitting his project on time.