Why not "Those kids were in Delhi yesterday."
I know it's fine. But thats not one of the correct answers.
कल दो तरह के होते हैं...
The sentence has "thay" in it which has a past tense connotation so the "kal" in the sentence must mean "yesterday"
Is there any rule to use yesterday,today,tomorrow and the day before yesterday?
कल, आज, कल, and परसों
They are used the same way as in English, and the meaning of कल is implied for the conjugation: वह कल गया = He went yesterday. वह कल जाएगा = He will go tomorrow.
Also, why is New Delhi flagged as wrong?
New Delhi is नयी दिल्ली