Choose the correct indirect sentence of the following direct sentence…

The correct answer is Option (3) → My teacher often tells me that if I don't work hard, I will fail.

Reporting verb in the present tense:

Change	Direct	Indirect	Why
Reporting verb	says to me	tells me	“Says to me” becomes “tells me”, still in the present tense.
Tense kept	don't work, will fail	don't work, will fail	When the reporting verb is in the present, the tense of the reported words does not change. “Don't work” and “will fail” stay as they are.
Pronoun change	you, you	I, I	“You” (the listener, that is, me) becomes “I”.
Joining word	“ ”	that	The inverted commas are replaced by “that”.
Full sentence	My teacher often says to me, “If you don't work hard, you will fail.”	My teacher often tells me that if I don't work hard, I will fail.

Example: She says, “I am busy.” → She says that she is busy.

Why the Other Options are Incorrect?

Option 1: My teacher often told me that if I don't work hard I would fail. — Incorrect. The present "says" is wrongly changed to "told", and the tenses inside are mixed ("don't" with "would").

Option 2: My teacher told me if I don't work hard I shall fail. — Incorrect. "Often" is dropped, the reporting verb is put in the past, and "will" is changed to "shall".

Option 4: My teacher says to me if I didn't work hard I shall fail. — Incorrect. "Says to me" is kept without "that", and "didn't" and "shall" wrongly change the tenses after a present reporting verb.