Select the option that expresses the given sentence in reported speech.
He said, "I have been working on the project for months".

Correct option is D

Direct Speech- it means reporting the message of the speaker in the exact words as spoken by him.
Indirect Speech- It is speech which tells you what someone said, but does not use the person's actual word.
· Given sentence is a direct speech.
While changing direct speech into indirect speech following rules are to be followed:
· Tense Change: The present perfect continuous tense "have been working" typically shifts to the past perfect continuous tense "had been working" in reported speech, especially when the reporting verb is in the past tense ("said").
· Direct to Indirect: Remove the quotation marks and integrate the statement with a reporting clause using "that."
Option (d) is the correct choice as it accurately transforms the original direct speech into reported speech by adjusting the tense and maintaining the same temporal context and meaning.