Identify the part containing a grammatical or structural error:
He asked me that where I was going.

Correct option is D

Option (d) contains an error.
Detailed explanation: In indirect questions, we do not use the conjunction that before the interrogative word ( where/when/why/how). The correct structure is: ask + object + wh-word + clause. Therefore, “He asked me where I was going” is correct, not “that where.”
Grammatical rule used: In reported (indirect) questions, use: Reporting verb (asked/inquired) + object + wh-word + subject + verb; do not use that with wh-words in questions.
Example:
• Direct: “Where are you going?” he said to me.
• Indirect: He asked me where I was going.
Information booster / exceptions:
• If the direct question is yes/no, we use if/whether: “He asked me if I was fine.”
• With wh-words, keep the wh-word and change tense/pronouns/time markers as per backshifting rules; don’t add that.