In the following direct and indirect speech question, choose the reported speech sentence that correctly converts The policeman said, "I saw a knife here." into indirect speech.

Introduction / Context:
Questions on direct and indirect speech are very important in English grammar sections of competitive exams. They test whether a learner can correctly change quoted speech into reported speech while adjusting tense, pronouns, and adverbs of place or time. In this question, a statement made by a policeman is given in direct speech, and you need to select the correct indirect version. This skill is useful not only in exams but also in real life when summarising what someone said without quoting them exactly.

Given Data / Assumptions:
- Direct speech: The policeman said, "I saw a knife here." - Reporting verb: said (in simple past tense). - Reported clause: I saw a knife here. - The task is to apply the normal rules of changing direct speech to indirect speech for a statement.

Concept / Approach:
When changing a statement from direct to indirect speech, three changes are especially important. First, if the reporting verb is in the past tense, the tense in the reported clause usually moves one step back, so simple past becomes past perfect. Second, the pronoun "I" must be changed according to the speaker, here the policeman, so it remains "he". Third, words indicating place or time, such as "here" and "now", are often changed to "there" and "then" when the reporting is done from a different location or later moment. For a neutral report, the reporting verb "said" is generally followed by "that".

Step-by-Step Solution:
Step 1: Identify the reporting verb "said". It is in the simple past, which means the tense in the reported clause should usually shift back. Step 2: The original clause "I saw a knife here" uses simple past "saw". In indirect speech, this should change to past perfect "had seen". Step 3: Change the pronoun "I" to "he", because the speaker is the policeman and the reporter is narrating third person speech. Step 4: Replace the demonstrative adverb of place "here" with "there", because in most indirect speech conversions, the location is described from the reporter point of view, not the original speaker position. Step 5: Introduce the reported clause with "that" after "said" for a standard formal structure. Step 6: The resulting sentence is "The policeman said that he had seen a knife there.", which matches option b.

Verification / Alternative check:
To verify, mentally check each option against the rules. Option b, "The policeman said that he had seen a knife there.", correctly uses past perfect, correct pronoun, and changes "here" to "there". Option c, although it adjusts pronouns and tense, still keeps "here", which is not ideal when converting to reported speech. Option a introduces "exclaimed", which suggests strong emotion not present in the original matter of fact statement. Option d uses "told" without an object, which is grammatically incomplete, since "told" usually requires someone to be told. This systematic check confirms that option b is the only fully correct answer.

Why Other Options Are Wrong:
Option a is wrong because "exclaimed" changes the tone of the sentence and still retains "here". The original sentence does not show surprise or strong emotion. Option c is wrong because it keeps "here" instead of "there", which is not the standard transformation when the point of reference changes. Option d is wrong because "told" requires an object, such as "told me" or "told us", and without that object the sentence is incomplete and ungrammatical.

Common Pitfalls:
Many learners remember to change tense and pronouns but forget to adjust adverbs like "here", "now", "today", and "tomorrow". Another common error is changing the reporting verb to something stronger like "exclaimed" without any evidence of emotion in the original. Candidates also sometimes use "told" in every context, ignoring that "said" and "told" do not behave identically. Careful practice and attention to each element of the sentence are necessary to avoid these mistakes.

Final Answer:
The correct reported speech sentence is The policeman said that he had seen a knife there.