Answer is Right!
Answer is Wrong!
The correct answer is D.
The Principal asked me whether I had informed the Chief Guest the revised schedule the day before. This means that the Principal does not know whether or not I informed the Chief Guest the revised schedule the day before. The Principal could have asked me in a number of ways, but the most likely way would be to say, “Did you inform the Chief Guest the revised schedule yesterday?”
Option A is incorrect because the Principal is asking me, not himself.
Option B is incorrect because the Principal is asking me about something that happened in the past, not something that is happening now.
Option C is incorrect because the Principal is asking me about something that happened yesterday, not the day before.