In this direct and indirect speech question, convert the sentence “He said to the bankers, \\"These diamonds are more valuable than a billion dollars.\\"” into correct indirect speech by choosing the best option.

Introduction / Context:
This question asks you to report a statement comparing the value of diamonds with a billion dollars. The original direct speech contains a demonstrative pronoun “these,” the present tense “are,” and a comparative structure “more valuable than.” When converting this to indirect speech, you have to adjust the reporting verb phrase, the demonstrative pronoun, and the tense, while keeping the comparison intact and grammatically correct.

Given Data / Assumptions:

• Direct speech: “He said to the bankers, ‘These diamonds are more valuable than a billion dollars.’”
• “Said to the bankers” should be converted to “told the bankers” in indirect speech.
• The demonstrative “these” normally becomes “those” when the statement is reported later or from a different point of view.
• The present “are” usually backshifts to “were” after a past reporting verb.
• The comparative phrase “more valuable than a billion dollars” remains structurally the same.

Concept / Approach:
The key reported speech ideas here are changing “said to” into “told,” shifting demonstratives from near to distant (these to those), and backshifting the present tense to past tense. The comparative structure itself does not change beyond the tense of the linking verb. The correct indirect sentence will therefore say that he told the bankers that those diamonds were more valuable than a billion dollars.

Step-by-Step Solution:
Step 1: Replace “said to the bankers” with “told the bankers,” giving “He told the bankers …” Step 2: Introduce the reported clause with “that,” resulting in “He told the bankers that …” Step 3: Change “these diamonds” to “those diamonds,” reflecting the shift from direct to indirect viewpoint. Step 4: Backshift the present tense “are” to “were,” because the reporting verb is in the past. Step 5: Keep the comparative phrase “more valuable than a billion dollars” intact. Step 6: Combine these elements to form “He told the bankers that those diamonds were more valuable than a billion dollars.” Step 7: Compare this sentence with the options and select option D as the correct one.

Verification / Alternative check:
Examine the other options for errors. Option A contains “then” instead of “than,” which is a spelling mistake and changes the meaning of the comparative expression. It also keeps “these diamonds are,” failing to change “these” to “those” and “are” to “were.” Option B uses the present perfect “has told” and includes an awkward phrase “this that,” which is stylistically poor. Option C correctly changes “these” to “those,” but keeps “are” instead of “were,” not following the normal backshift rule. Only option D applies all the changes consistently and remains grammatically smooth.

Why Other Options Are Wrong:
Option A uses the incorrect word “then” instead of “than” and keeps the demonstrative and tense unchanged, both of which are errors. Option B changes the reporting verb to “has told,” which does not match the simple past “said,” and the structure “this that” is unnatural. Option C uses “those diamonds” but retains “are,” ignoring the need to backshift the tense after a past reporting verb.

Common Pitfalls:
Learners often overlook small but important distinctions between “than” and “then,” or between “these” and “those.” They may also forget to backshift “are” to “were” in reported speech. Another pitfall is to change the reporting verb form unnecessarily, leading to tense mismatches. To avoid such mistakes, check spelling carefully in comparative structures, be mindful of demonstrative pronouns, and always ask whether the tense of the reported clause needs to move back in time relative to the reporting verb.

Final Answer:
The correct indirect speech version is “He told the bankers that those diamonds were more valuable than a billion dollars.”