Transform the sentence into indirect speech; 'I said to him, why are you working so hard?'
ক
I asked him why had he been working so hard.
খ
I asked him why he had been working so hard.
গ
I asked him why was he working so hard.
ঘ
I asked him why he was working so hard.
সঠিক উত্তর: I asked him why he was working so hard.