In the following question, a sentence is given in direct speech. Select the option that best expresses the same sentence in indirect (reported) speech. He said, "I had not received the passport hence I could not attend the conference held last year."

Introduction / Context:
This question deals with reporting a reason for being unable to attend an event in the past. The direct sentence uses past perfect to show a previous non receipt of a document and a modal structure "could not attend" to show resulting inability. The learner must report this correctly, ensuring that tense, connectors, and overall meaning are preserved.

Given Data / Assumptions:

• Reporting verb: "said" in simple past.
• Direct speech: "I had not received the passport hence I could not attend the conference held last year."
• First person pronoun "I" refers to "he" in reported form.
• Verbs: "had not received" (past perfect) and "could not attend" (modal showing inability).
• Time expression: "last year" refers to a completed time in the past.

Concept / Approach:
Past perfect generally remains past perfect when we report speech with a past reporting verb. Modal "could" usually does not change, because it already refers to past ability or possibility. The time expression "last year" may remain as it is if the distance in time is still clear, and many exam keys accept this usage. The linking word "hence" shows cause and will usually remain unchanged, although "so" is also common in everyday usage.

Step-by-Step Solution:
Step 1: Begin the sentence with "He said that" to introduce the reported clause. Step 2: Change pronoun "I" to "he" in the reported version. Step 3: Keep "had not received the passport" unchanged, because the past perfect form already shows the earlier non receipt and does not require further backshifting. Step 4: Retain the causal connector "hence" to show the reason for the next action. Step 5: Keep the modal phrase "could not attend the conference" unchanged, since "could" already refers to past inability. Step 6: Keep "held last year" as "held last year", because the conference time remains clearly in the past relative to the reporting moment. Step 7: The final form is "He said that he had not received the passport, hence he could not attend the conference held last year."

Verification / Alternative check:
Check that the cause and effect relation is preserved: first, failure to receive the passport; second, inability to attend the conference. The reported sentence keeps both actions in the past and clearly linked. No unnecessary tense changes are introduced, and the structure remains natural and correct according to standard grammar rules for reported speech. The past perfect and the modal "could" correctly represent the original meaning.

Why Other Options Are Wrong:
Option A wrongly uses "could not be attending", which suggests a continuous action and does not match the simple completed event of attending a conference. Option B changes "had not received" to "has not received" and also changes the time phrase to "the month before", which is inaccurate because the original refers to last year, not last month. Option D again uses present perfect "has not received" and "could not be attending", making both tense and aspect incorrect.

Common Pitfalls:
Learners sometimes think that every verb must change tense in reported speech, even when it is already in past perfect or when a modal verb is present. This leads to unnatural or incorrect forms. Another common mistake is to alter the original time phrase loosely, which can change the meaning. When working with reported speech, it is important first to understand the original time relationship and then decide whether backshifting is required or whether the original tense and expression already show the correct time frame.

Final Answer:
The correct reported sentence is He said that he had not received the passport, hence he could not attend the conference held last year.