Rewrite the sentence in indirect speech.
Sunder said, "I will go to my sister's house today."

Correct option is D

Explanation: The future tense "will go" in direct speech changes to "would go" in indirect speech. The expression "today" changes to "that day" to reflect the time change in reporting.
Grammatical rule used: Change from future tense to conditional tense and temporal expressions to match the time of reporting in indirect speech.
Example: "I will visit the museum today," she said. -> She said that she would visit the museum that day.