A sentence has been given in Active/Passive voice. Out of the four alternatives suggested

A sentence has been given in Active/Passive voice. Out of the four alternatives suggested, select one which best expresses the same sentence in passive/active Voice.

IGNOU books are being sold here at half the price by the old students of our university.

A.            The old students of our university are selling Ignou books here at half the price.

B.            The old students of our university are been selling Ignou books here at half the price.

C.            The old students of our university are being sold Ignou books here at half the price.

D.            The old students of our university were selling Ignou books here at half the price.