In the following question, a sentence is given in Direct speech. Out of the four alternatives, select the option that best expresses the same sentence in Indirect (reported) speech: He has just said, "My son will be back on Friday."

Introduction / Context:
This question tests the rules of converting a sentence from Direct speech to Indirect (reported) speech when the reporting verb is in the present perfect tense. The direct sentence is: He has just said, "My son will be back on Friday." You must identify which option correctly reports this sentence without changing the meaning, tense, or time reference.

Given Data / Assumptions:

- Reporting clause: He has just said. - Reported clause: "My son will be back on Friday." - Reporting verb tense: present perfect (has said). - Speaker is "he", and the owner of "my son" is also "he". - The future time expression is "on Friday".

Concept / Approach:
When the reporting verb is in the present or present perfect tense, the tense inside the reported clause usually does not change. The quoted future form "will be back" therefore remains "will be back" in Indirect speech. However, pronouns and possessives need to be adjusted according to the perspective of the reporter. The first person pronoun or possessive "my" changes according to the subject of the reporting verb. Here "my son" must become "his son" because "he" is the speaker. Time expressions like "on Friday" remain the same because the time reference has not shifted.

Step-by-Step Solution:
Step 1: Identify the reporting verb and its tense: "has just said" is in the present perfect, so no tense backshift is needed. Step 2: Remove the quotation marks and introduce the conjunction "that" to connect the clauses. Step 3: Change the pronoun "my" to "his" because the speaker is "he" and he talks about his own son. Step 4: Keep the future tense "will be back" unchanged, as the reporting verb is not in the past. Step 5: Keep the time expression "on Friday" as it is because the reference point is still current. Step 6: The correct reported sentence becomes: He has just said that his son will be back on Friday.

Verification / Alternative check:
To verify, convert the correct Indirect sentence back to Direct speech. From "He has just said that his son will be back on Friday", we can reconstruct: He has just said, "My son will be back on Friday." The tense, time expression, and meaning all match the original sentence. This confirms that the structure and pronoun change are correct. None of the other options give this exact reversible relationship while preserving grammar and sense.

Why Other Options Are Wrong:
Option A uses "my son", which wrongly suggests the listener is the speaker, not "he". Option C replaces "will" with "shall", which changes the original auxiliary and is not required in this transformation. Option D changes "will be back" to "would have been back next Friday", which alters both the tense and the time reference and completely changes the meaning.

Common Pitfalls:
Learners often think that the tense must always change when going from Direct to Indirect speech. In reality, when the reporting verb is in the present or present perfect, the tense inside the reported part usually stays the same. Another frequent error is to forget to shift the possessive pronoun from "my" to "his" or "her" depending on the subject of the reporting verb. Confusing time expressions like "Friday", "that day", or "the next day" is also common. Always check whether the point of reference for time has actually moved into the past before changing these expressions.

Final Answer:
He has just said that his son will be back on Friday.