Choose the most appropriate indirect construction of the given senten…

The correct answer is Option (2) → She whispered that she shouldn't have said that.

Statement in indirect speech:

Change	Direct	Indirect	Why
Joining word	“ ” (inverted commas)	that	“Whispered” stays, because it tells how she spoke. The reported statement is joined with that and the inverted commas go.
Tense kept	shouldn't have said	shouldn't have said	“Shouldn't have said” is a modal perfect. “Should” has no further past form, so it stays the same.
Pronoun change	I	she	“I” becomes she.
Full sentence	“I shouldn't have said that,” she whispered.	She whispered that she shouldn't have said that.

Words of nearness (time and place): "that" already points away from the speaker, so it stays "that".

Example: “I should have called you,” he said. → He said that he should have called me.

Why the Other Options are Incorrect?

Option 1: She whined that she shouldn't have said so. — Incorrect.

• "Whined" (complained in a high, unhappy voice) changes the way she spoke. She whispered.
• "That" is changed to "so", which alters her words without need.

Option 3: She regretted having said this earlier. — Incorrect.

• It is a summary of her feeling, not the reported form of her words. "Whispered" is lost.
• "That" becomes "this" (a word of nearness in the wrong direction), and "earlier" is added.

Option 4: She whispered that she shouldn't have been saying that. — Incorrect. "Shouldn't have been saying" is the perfect continuous. It turns a single remark into an action going on over time. The modal perfect should stay unchanged.